Hmmm, how do you do that? Seriously, I'm socially inept at times and this is just the kind of hole I dig myself into on a daily basis. If you say you think people that do X are morons and then someone around you admits that they do X, what do you say? You can stick to your guns and say "well then, sorry, but that's what I think of you", which probably falls under that rude category. You can back down on your position and say "well not you of course" which is more polite I guess, but never seems genuine and abandons your opinion entirely. And then there's the option of just saying nothing at all and basking in the uncomfortable silence that will inevitably follow.

I've got this co-worker who is my age but has THE most fuddy-duddy taste ever. She collects "Precious Moments" figurines for god's sake! I am constantly caught in situations where I'm expressing an opinion of disdain for things she just loves and I can't seem to dig myself out.