Which shows did you start out loving, but end up hating? For me, Buffy is the ultimate example. I so love the first three seasons, one of my favourite shows ever. The fourth season was already disappointing, but it just got worse and worse after that. It turned into something I would've avoided at all costs. I like to pretend the rest of the show simply doesn't exist.
shareUK show Misfits. Awesome to begin with really quirky. Then after the third season main cast members left, the new ones didn't seem as interesting or appealing. I think by the time the show ended there weren't any originals left, from memory anyway I could be wrong.
NCIS, once DiNozzo left this show was dead. They pumped in new cast members but they were all bland, then Abbie left and they replaced her with someone who was trying to do the same quirky thing but it's not working.