After reading these replies, it turns out that this is way more common than I realized. Yeah, there's the few who said that it's a dumb thing to do, but there's a significant group here who said that they end up disliking something simply because someone they don't like happens to like or love it. Perhaps maybe it's a thing of "I don't like him, so he's wrong about everything, so everything he likes must automatically be terrible, including something I once loved."
Well, I tend to do this almost every minute of the day. It's gotten to the point where I'll check social media and such to see what else they like and dislike, and then sort my interests and such based on these. Either that, or have the mindset to abandon EVERYTHING I once loved and then create stuff myself.
Things I now hate because of other people:
Banjo-Kazooie
The Sonic Franchise
Modding
Linkin Park
Alice in Chains
Practically any popular video game
Any opinions they have
That's the tip of the iceberg. Heck, I'd go as far to say that I'd change my ORIENTATION to have less in common with these people.