In any walk of life I don't especially like being around people with prejudiced attitudes, but as others have said, sometimes it's deeply ingrained because of where someone grew up. So yes, it bothers me and I will always try to steer conversation away from things like this (politics, religion, race etc - and in any case, they aren't exactly the most hot and steamy conversations to get me in the right mood).
The worst example of this I ever had was years ago - a girl who didn't seem to like the fact that I wasn't buying her 9/11 conspiracy theories (I'm not quite sure why I got so involved in that conversation either, apart from that none of her argument was based on any kind of fact or evidence, which really bugs me when you talk to anyone). By the end of that conversation, it was clear that I didn't like her on any level and she felt much the same way. Crap BJ, crap punt, no sex.
After that I resolved that any conversation with WGs should always be steered back towards 'what do we both like sexually', should never go any deeper than the classic 'going anywhere nice on holiday?' conversation you might have with a hairdresser, and that if in doubt, I should express no opinions on anything a WG has to say.