In "Stuck In Ed", Eddy does a scam involving getting the cul-de-sac kids to submit their ideas of a scam to the Eds, Jimmy gives them an idea, Jimmy's scam involves 10 extension cords, 10 refrigerators, 100 fenceposts, various fruits and many gallons of water, it turns out that Jimmy's idea for a scam involves Ice Pops. You'd think: That even for as childish a scam as it is, Eddy would see potential and use Jimmy's scam in the future. Instead: Being Eddy, he angrily rejects the scam. Result: The Eds don't get a buck the next time they cook up a scam., Great going, Eddy.
At one point, the Eds literally get stuck inside Johnny's wall, presumably to avoid the Kankers, and need a way to get out. You'd Expect: The Eds, particularly Ed and Eddy, frequently showing abnormal physical strength, to break through the walls no problems. Instead: They waste time by making up stories and eventually get attacked by the Kankers (who aren't really 200 feet tall) again.
Double D is handed what appears to be a can of jelly beans. Double D is standing in an abandoned factory originally used for pranking toys, with two guys known for pulling pranks; in fact, Double D had just been pranked by the other two Eds into believing they had been killed by a supernatural figure. Also, the Eds are on the run from the kids, and can't afford to attract any attention to their position. Finally, we're talking about a guy who actively lampshades his being Surrounded by Idiots on a regular basis. You'd Expect: Double D would suspect that Ed's follow-up offer, quite possibly thought up by Eddy, for a can of jelly beans was a trick. After all, "fool me once, shame on you, but fool me twice, shame on me". Instead: He just accepts the offer, not suspecting anything at all during the whole minute he tries opening the can. The result? The can causes an explosion of many rubber snakes being spewed all around the factory's area. Kevin, who was in the area with Nazz, realized where the Eds were hiding, although this didn't help them all that much in catching the Eds, since they move on anyway. Of course, Double D himself was propelled by the explosion, and ended up stuck to a rock high up on a waterfall.
In "Brother, Can You Spare an Ed?" Sarah entrusts Ed with her money to buy her and Jimmy some fudge at the candy store. Eddy, the greedy jerk he is, wants Ed to buy jawbreakers, but Edd insists that it is Sarah's money, so it should be spent to her specifications. You'd Expect: One of should realize the threat Sarah poses if her for once reasonable request is not met. Instead: Edd and Eddy argue over the proper usage of the money, representing integrity vs. Greed, respectively, until impressionable Ed enters the store and gives into temptation, only remembering that Sarah intends on kicking their asses when it is too late. Well, we would not have a show if they did not get into these jams.
For a majority of the show, the Eds devise a scam to get the kids' money. You'd Expect: The kids would eventually catch on and not give them jack shit. Instead: They keep falling for it. Every episode.
Similarly, there occasionally comes times for when the Eds will need something that no one else seems to have/will be able to get/give them. Unfortunately, one of them will get the idea to go to the Kanker Sisters. You'd Expect: The Eds would be wise enough to avoid the girls that borderline sexually harass them every chance they get. Instead: They go right for the Kankers and end up with the same old ending of getting Covered in Kisses or otherwise.
In general, Adults Are Useless to the point where you question whether they care about their kids or not. The kids repeatedly get beaten up by other kids, blackmailed, raped, etc. You'd Expect: The parents to put restraining orders on others, call family/parents/child services, or someone to go up to them and call them out for neglecting their children. Instead: Nobody does any of that.
Within another infamous episode known as "Your Ed Here", Kevin discovers Eddy's Embarrassing Middle Name and uses it to blackmail him. You'd Expect: Eddy to tell Double D and Ed or his parents about the situation, especially since Double D being DoubleD and Ed being Ed, they would understand. Instead: He keeps it a secret to himself and lets them know at the last minute after Kevin humiliates him. Thus: Kevin doesn't get punished for what he's done.
Also, in the infamous episode "If It Smells Like An Ed," Jimmy confessed that he was the one who framed the Eds after Eddy humiliated him by giving him a wedgie. You would have expected: For Jimmy to target Eddy only because Eddy alone humiliated him. Instead: Jimmy targets Ed and Edd along with Eddy. I mean, why target two people who didn't do it?
Before that, the Eds invade the kids' Friendship Day, Jimmy offers to befriend them. You'd Expect: Eddy to get along with Jimmy and potentially the other kids and gets what he wanted; respect from his peers. Instead: His jerkass tendencies kicked in once more, he bullies Jimmy by wedging him in front of the other kids, thus causing Jimmy to do the above Evil Plan and the Eds end up humiliated. Freudian Excuse or not, Eddy really needs to lighten up.
Also, as mentioned above Eddy wrongly humiliates Jimmy by wedging him in front of everyone. You'd Expect: The kids or even Edd to attack Eddy or at least call him out for it. Instead: They all just stand there and laugh at his expense. Sarah has to step in to get them to stop.
During the climax of "Mirror, Mirror on the Ed", Eddy (who is currently dressed up as and forced to act like Ed) has to hide in Edd's house because of pissed off Kevin wanting to beat him up after Eddy teased him. Suddenly, the alarm in Edd's room activates for no apparent reason. You'd Expect: Edd, being The Smart Guy, constructing the alarm in a way that locks the burglar in or recognizes one of his friends. Instead: The alarm opens the door, allowing the potential burglar to escape, and Kevin to beat up Eddy.
The Eds and Kankers were in a "squirt-gun duel" and the Eds aren't landing any successful shots at them. You'd Expect: The Eds to realize they're wasting ammo and pull themselves together. Instead: They fired wildly, used up all their ammo, the Kankers remained unscathed, they incapacitate them by using a special sticky substance and the Eds endure yet another sexual attack from the Kankers.
In "Ed Overboard", Ed gets kidnapped by the Kankers and Edd and Eddy agree to let the Urban Rangers save him. At one point, Johnny and Jimmy are trying to untie Ed from a tree as Rolf distracts the Kankers, but then Ed yells and they tell him they won't help him if he isn't quiet. You'd expect: that Ed doesn't say anything and has Johnny and Jimmy save him. Instead: Ed decides that he should call for help even though they're trying to help him, and he loudly sings "London Bridge", thus making the Kankers catch them. Well, this is Ed we're dealing with here, but even he should know better. At least the Urban Rangers distracted the Kankers even more.
In the movie, after Eddy apologized to the kids and earned his happy ending, Johnny arrives and beats up the Eds, not knowing about the above. You'd Expect: The other kids will explain the situation to Johnny, seeing as he's unaware of the situation. Instead: They grab their Idiot and Jerkass Balls and beat him up, earning a new enemy (The Gourd). Honestly, they were about to do the same thing he did five minutes earlier.
Throughout the series, it's hinted many a time that Eddy's brother is a monster instead of the Cool Big Bro that he often says that he is. For example, one of his inventions is a gigantic stink bomb, he sends Eddy baby toys and apparently he did something to Rolf's chickens. You'd Expect: That the other kids and Double D and Ed would catch on eventually. Instead: Eddy does everything to hide his brother's true nature, and we don't learn the truth until the movie.
The movie shows that Kankers really care about the Eds. Despite their constant abuse, Edd and Ed are still more afraid of than spiteful towards the Kankers. If Marie and May tried to be nice to them, Ed and Edd, being both very kind and accepting, would have easily accepted the girls, at least as friends. You'd Expect: Marie and May to realize that their schtick doesn't work and just try to befriend them. Instead: They continue tormenting Edd and Ed.
In "Avast Ye Eds," when the Eds are in their tire float, the Kankers launch a bobby pin on it and the pin gets stuck. Eddy walks over to the spot and Edd tells him not to pull it. You'd Expect: For Eddy to listen to Edd and not to try to pull the bobby pin off. Instead: He foolishly pulls the bobby pin off, causing the float to deflate and the gang to land in the water and the Kanker Sisters to kidnap them on their boat. Then: Jonny and Jimmy are forced to walk the "Plank", and the Eds end up getting raped again. Happy ending, indeed.
In "Little Ed Blue", Ed has gotten cranky and Eddy and Edd (well, mostly Edd) try to help him. They then spot Kevin pitching baseballs at Ed's head. You'd Expect: Kevin to leave Ed alone knowing that he could crush him. Instead: He (along with Eddy no less) keeps on annoying Ed. The Result: Ed forcefully morphs Eddy into a baseball bat and whacks Kevin with it.
In the episode "Smile For The Ed," Eddy wants to take a good picture of himself to show to his mother. However, Kevin ruins Eddy's picture by calling him a dork while he poses for it, and the picture ends up looking horrible. You'd Expect: For Eddy to just report Kevin's bullying to the principal, to insure that Eddy can retake his picture without Kevin interfering. Instead: The Eds attempt to retake the photo and Edd ends up impersonating the principal, which ends in chaos and with the Eds getting detention, while Kevingets off scot-free However: Since Adults Are Useless, it's likely that Failure Is the Only Option.
In "Truth or Ed", Eddy gives himself a false identity (Bobby Blabby) to create lies about the kids. But Ed eventually makes him confess the truth. You'd Expect: Eddy to keep his mouth shut when Ed mispronounced his false name. Instead: Eddy blurts out "IT'S BOBBY BLABBY, GET IT RIGHT!" in front of the kids, thus blowing his own cover. The Result: Knowing who Bobby Blabby really was, the kids punish Eddy by having him knit the world's largest doily.
In "Here's Mud in Your Ed", Rolf and Jimmy fool Eddy into believing simple objects are money tree seeds. So he gives up all his possessions in trade. And he falls for it twice. You'd Expect: Eddy to realize he's been played the second time around. Then again, he shouldn't have fallen for it the first time since there's no such thing as a money tree. Instead: After angrilly consulting Rolf for conning him, he falls for it a second time. Ed himself replies "Even I am not that dumb, Double D".
A man (Eddy's brother) lives at an amusement park, this same man tortured and bullied his younger brother for a good whole of his life, and it's implied that he lives at this park so he can torture children. You'd expect: Somebody should have the cops raid the place or something. Instead: Nobody does bugger-all about it.
In the episode "All Eds Are Off", the Eds, Rolf, Kevin, and Jonny take part in a bet, with the cash prize of $1.25 given to the person who can give up on an annoying habit of theirs the longest. Eddy (of course) attempts to cheat by getting the others out by tempting them. He starts off with Kevin, who has to give up on calling the Eds "dorks" You'd Expect: For Kevin to see what Eddy is trying to do, and find another word to call him besides "dork." Instead: Kevin gives into Eddy's taunting and starts shouting the word "dork" repeatedly. Thus: Kevin loses the bet.
Also, Eddy's next target to tempt is Edd. Edd has to stop using big words and can only form sentences with 4 syllables. Eddy tempts Edd by tearing out pages from a dictionary. You'd Expect: For Edd to make up a sentence with 4 syllables to get the book from Eddy, or matter fact, just snatch the book from Eddy without saying a word. Instead: He gives into temptation and starts using big words, thus losing the bet.
At the very end, when Ed jumps into a gravy-like liquid and appears to lose the bet, Eddy is happy and wants to rejoice. You'd Expect: For Eddy to read the label of the can to assure that it's gravy, to make sure Ed really lost the bet. Instead: Eddy starts to celebrate that he won the bet, and starts shouting really loud. However: When it's discovered that the "gravy" that Ed jumped into was in fact butterscotch, Eddy gets upset and then puts his hand over his mouth, realizing he lost the bet.
The episode "Too Smart for His Own Ed" just clarifies how dumb the characters are, following Edd's mistake in a spelling bee. You'd Expect: The kids would have treated Edd the same way even if he got one word wrong. Instead: Just for mispelling the word "Gravy", everyone treats him like an idiot, preferring to have ED help them with a test.