I don?t get it either. I like Power Rangers, despite its shallow plot and stock one-dimensional characters and god-awful acting and cheaply reused animation, but it?s just so bombastic and nostalgic that I don?t care about that and watch it for the awesome. It?s a bad show, but it appeals to the child within me. Same goes for Dragon Ball Z (well, minus the long standing-around; I can do without that, but the actual fights, yes).
As for my brother, he likes the Final Destination films (for different reason than I do; I genuinely do find them to be good popcorn flicks with a fair amount of suspense the first time around) because he finds the over-the-top death scenes hilarious.
Liking something because it?s bad either means you?re trying too hard to be a quirky little hipster or whatever (because there?s no-one to laugh at how ?IRONIC!? you?re being if you?re just watching My Little Pony at home), or you?re just genuinely masochistic. No-one should be ashamed for liking something, unless it?s illegal and immoral like killing puppies or something. But for something like entertainment media?no-one under the age of 13 should give a damn what others think about their hobbies.