Straight: Emperor Evulz has just captured the heroes Alice and Bob for intruding in his evil lair. Instead of shooting them, he suspends them over a Shark Pool, explains his evil plan to turn the world's gold reserves into cheese, and leaves them alone in the room as an automatic lowering mechanism slowly lowers the pair down to the sharks below. They escape.
Exaggerated: After escaping the Shark Pool by instantly degrading all the sharks' teeth with an experimental calcium disintegrator and using the pool ladder, Alice and Bob run out of the room just to fall right back into Evulz's clutches. The pair have just escaped his Death Trap, Emperor Evulz has a loaded gun in his hand and two dozens of armed guards at his beck and call, and his Number Two is asking "Why don't we just shoot them?". Evulz has the pair marched right back into the room and suspended over the pit full of now toothless sharks, alongside with Number Two for gainsaying him, and reiterates the plot to them down to the finest detail and throws in an Evil Laugh for good measure. He then leaves his Evil Lair along with all his other guards, leaving Alice and Bob (and a repentant Number Two) alone in his base of operations with free access to all his maps, plans and his Patented Turn-Cheese-Back-Into-Gold-Ray only a new escape away.
Downplayed: Evulz tries to kill Alice and Bob with a method that is relatively practical, but still less efficient than straight-up shooting them.
Alice and Bob are Immune to Bullets, stabbing, and other forms of instant death. Only a slow and inefficient Death Trap, like dying of drowning and seafood allergies in his Shark Pool, will do the trick. Evulz has neither the time to stick around and watch them die (that Evil Plan won't finish itself) or the budget to post guards or cameras in the room.
Or it is established earlier in the plot that Evulz just loves being evil too much for his own good. While he could just shoot the heroes, it would take all the fun out of it. And he doesn't tell them his evil plan, he brags about it. It's not about winning, it's about the fun. For him it is just a game.
Alice and Bob finally catch up to Evulz after leaving his plan and organization in shambles. They run him through with nary a word.
Alternately, Evulz is defeated by Alice and Bob, but instead of executing him on the spot, the heroes put him through a long series of trials and jail sentences, which gives Evulz plenty of opportunity to plan an escape.
Evulz marches the pair to the Shark Pool and suspends them over it, leaves the room... And comes back with a handheld DV camera, a comfy couch, popcorn, a big grin on his face, and a cadre of armed guards with machine guns "just in case".
Evulz marches the pair to the Shark Pool and suspends them over it, leaves the room...and while he's away they are lowered in and eaten alive. It works, and they die horribly.
"Ah, screw it, my poorly designed death trap's probably not gonna work, anyways." "So we can go free?" "Of course not. Lock them in the airtight storage shed!"
He then mounts the camera on a tripod, fixes it on the point of impact, and leaves with the couch, popcorn and the guards. Alice and Bob are left alone to die slowly, painfully and inefficiently.
"Ah, screw it, my poorly designed death trap's probably not gonna work, anyways." "So we can go free?" "Of course not. Stick them in the backup trap!"
Zig Zagged: Having finally captured Alice and Bob, Evulz has them sent to the Shark Pool. Halfway there, he changes his mind and decides to bring them back to his throne room to be shot in front of him. Evulz changes opinion back and forth over whether he wants a slow, painful death or a quick, practical one, leaving Alice, Bob and guards to walk back and forth through the corridor between the throne room and Shark Pool as Evlulz constantly changes his mind. After the eight time they're ordered to turn around, Alice and Bob get enough, kick the guards in their shins, and escape while still handcuffed.
Averted: Evulz is not in the habit of using gloating or death traps. Whenever he captures heroes, he either kills them on the spot or has them sent to his sensibly-constructed and constantly monitored dungeons for processing, interrogation and death by firing squad.
Enforced: The writers want to show the villain is powerful enough to capture the hero. But they obviously can't have a story if the hero gets killed either.
Invoked: "And now that I have you captured, in accordance with the great villain traditions, it is time for me to place you in my slow-working and inefficient death trap to be killed offscreen, while I laugh evilly and rant to you about all my evil plans! Bwa ha ha ha ha!... Damn, I dropped my 'How to be a Bond Villain' check-list. Could you tell me if I missed anything?"
Discussed: "...Wait, he's just going to leave us in here to die?" "Yeah, it's pretty standard procedure for people like him."
Conversed: "Have you noticed that villains just never seem to be able to kill the heroes when they have the upper hand? It's always death traps, or being left for dead, or evil gloating and taunting with them."
Deconstructed: Emperor Evulz fails to kill Alice and Bob upon their first encounter due to wanting to be dramatical. Over the years, the pair escape from his fiendish devices time and time again, becoming stronger and smarter each time and driving Evulz over the brink as his decaying mind becomes too fixated on his failures and on their initial encounter to recognize that the Death Traps never work. In the end, when Alice and Bob finally break down the door to his inner sanctum, they discover a gibbering mental wreck driven mad by his own failures and decide to just Mercy Kill him for his own good.
Reconstructed: ...The corpse instantly vanishes, revealing itself to be a hologram. But what's this? Shock and horror, the 'inner sanctum' is not a sanctum at all, but a disguised tunnel with a slowly-moving Conveyor Belt-O-Doom that ends in a giant Lava Pit! From a previously-hidden loudspeaker that leads to his secret control room, Emperor Evulz taunts our dynamic duo with how foolish they were to fall for such an obviously transparent ruse. After saying a final mocking goodbye, Evulz turns the doom-belt on maximum speed and leaves the surely-doomed heroes to their inevitable fate while he gets some real work done elsewhere.
And now, being mesmerized by the secret hypnotic subtext I left in the page's writing and helplessly in my clutches as you are, I shall leave you here on this page to die slowly and painfully from radiation poisoning from your monitor, with only this handily crafted link to bring you back to Bond Villain Stupidity! Bwa ha ha ha ha ha... Wait, NOOOOOOOOOOOOOOOOO!