I know plenty of people who dislike metal and yet haven't given it a chance, I also know plenty who dislike it and have tried to listen to some, but the reason they give is either "Its noise" or "Its just shouting" or "Its just songs about death". They simply don't like it, just like I don't like pop. I hear far more "It's just noise" comments about metal from other fans than I hear insults towards other music from metal fans. I've been at a mates house before late night when everyone's just been sitting talking while people put music on on the PC, and I don't get up and turn off the rap that they put on, but I put on a metal song (even though the guy who's house it is likes metal) and someone will be up within 30 seconds to change it with a muttering of "What is this shit". In my experience there is far more intolerance towards metal in EVERY aspect - music, culture, fans, the works - than there is from it. Quite often I can put on a song to one of my sisters and as long as I don't say what it is they will listen and enjoy it, ask what it is, and when I say they go "... oh." and all the interest disappears from them, as soon as it's known to be metal they are put off. It's quite a common occurrence.
I will quite frequently say "I just don't like pop music", because it's far easier than saying "I have not yet discovered pop music that I enjoy and don't have the time to explore every possible album looking for one that I do".