Seriously, the old adage "if you have nothing nice to say, don't say anything at all" really rings true here. Every time....EVERY FUCKING TIME....someone comes to a concert where I perform and has some snide remark about "who chose that music?" or "that composer needs his ears checked". Comments like this have been thrown my way for the last 18 years after every concert. Finally, I snapped. I said "this music is amazing and we love it!" Silence. After a series of breaking confidences, I was told I was over sensitive and should not take it personally. The use of "atonal" was thrown around very nonchalantly and in this case, incorrectly. If you're going to be an assjack, at least use the correct vocabulary.
I hope this person never comes back to a concert again. I will NOT stop being offended by his asshat remarks, nor will I stop telling him his opinions are not welcome unless I specifically ask. Which I won't. Some people really suck.
Then there are those who go over and above to be supportive. I love those people.