Crossover - Just like those gamer tshirts that you always see in middle/high school

Pretty sure you hit the nail on the head there. The batshit logic behind some crossovers is often "hey, these two things that are good MUST be twice as good together!" but then they make absolutely no sense together and the result just comes across as terrible.

Par exemple: Shoving Doctor Who and One Piece together is like putting candy floss on a cheeseburger.