These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ear Rape being used in poops. It was originally regarded a staple in YTPs, but nowadays, opinions divide between whether its annoying and a tell-tale sign of a Spaghetti-Dinner poop or Actually Pretty Funny and most poopers just don't know how to use it properly.
There is also much dispute among the YTP community over make-sense vs not-make-sense, flash vs non-flash, and what defines YTP.
Many older Poopers view the CD-I and video game cartoons — as well as various memes — as overused.
There's also the opinion that proclaiming in a video's title or description that it's a Poop defeats the entire purpose of Pooping: subversion.
Fanon: Some concepts not present in the source material have transcended the videos they originated from to become commonly accepted in almost any poop.
Hyrule's royal family living in Ludwig's Castle Hotel from Hotel Mario is one example. Some Poopers change the name on the castle or remove it, but others, even a few who use Sony Vegas and easily could, leave the name intact.
King Harkinian's "Munf Munf" cereal is another that has transcended to become fanon, as well as his "Dinner Blaster".
Gateway Series: Some Poopers intentionally go out of their way to avoid using popular sources, and this can lead to fans looking up the originals.
Even the CD-I games and Dr. Rabbit were pretty obscure before Youtube Poop came along.
Michael Rosen Falls In Love. It's a cute story about Michael Rosen's teenage love interest. Then at the end, it goes into an alternate universe, in which Michael Rosen runs out and rapes her, causing her to transform into a terrifying creature called the "Blood Drinking Baby Eating Keel-Over-And-Die Foogle" and kill several people by shooting fire and plums out of her snatch:
All five of OrpheusFTW's skooks, while still funny, the entire thing feels like a nightmare someone had when they fell asleep watching Scooby-Doo.
*Twilight and the others disappear and are replaced by fire and the dancing thing from Chowder with disturbing music*
The second intro of the third KOTH "collab". After a pretty awesome intro, by Orpheus, we get Hank jumping out of the blue hole yelling demonically and then he pulls out a gun and shoots Dale and the screen.
Seinfeld Is Unfunny: Older-generation poops can be seen as this, particularly those that use what are now considered overused sources or memes. Repeated usage of "Mah boi", "Gay Luigi", etc. is now so old-hat that even most amateur poopers don't go for them anymore.