I don't like it that much either. It's overused among movie and TV show aficionados. Literally everything is and has a fandom, and in my mind it kind of refers to the basic bottom of the barrel of the entirety of a fandom.
See, I don't hate the idea behind fandom, but the tumblr fans have ruined it for me. It's like I love Sherlock/SPN/Doctor Who, but the fans have to say that the fandom made something "better" or that fandom is the best ever and it makes me start to hate those shows, and that's pretty much why I can't stand fandom anymore. Those fandomy types make it impossible for any other non annoying fans of the show to be seen. Like, I'm sure all of you just wanted to kill me after the first bit of the second sentence. Yet I'm not like the fandom. It's not fair that I have to defend liking those shows because of a bunch of idiot twelve year olds with tumblrs. I'm a fan of those shows, but I am by no means in the fandom.