4. "It's not my preferred genre, therefore I won't touch the thing."
(I'm also referring to people who haven't read works that pertain to a certain genre, but still say they hate that genre. For example, historical novels.)
Big mistake. Besides, I'm curious as to how exactly you can avoid a specific genre, since so many books today are a combination of at least 3 genres (films, even more, since they need to appeal to a wider public)! And that's precisely what makes them so good. What would comedy be without a hint of drama or romance? Anyone can do slapstick, but it takes someone good to mix stuff and get something more complex. How about parody? There is no limit to parody, it stretches freely across genres.
Aside from this (obvious) truth, keeping away from a book/film because it contains a specific genre is like not wanting to date a guy/girl because he/she is one year younger than you. How will you know what it's like if you don't try it? Why not give it a go, you might even like it!
Let's think about this another way: let's say you go out of your way to inform yourself on every book or film that doesn't pertain to the genre you dislike, and only stick to reading or seeing the rest. Don't hate me for this, but I think your life is completely boring. If you bother to research everything that in-depth, you're missing out on the thrill of doing something spontaneously.
Another example from my own life: for my 16th birthday I went out to a movie with a few friends. We were arguing between Yes Man and Sex Drive, finally deciding on the latter (I watched Yes Man eventually as well). While I hated it (as I usually hate teen comedies), I'm glad that I saw it, and you know why? Because it made me appreciate the good comedies I'd seen even more. So, you see, you need to be exposed to bad things to appreciate the good ones.
I also admit to having a penchant for watching bad films from time to time, whenever I feel like making fun of something. If you're like me, I suggest horror films with teenagers – they're a never-ending source of laughter, mostly because said teenagers are so stupid they make me wonder how they don't forget to keep breathing.