Thank you so much for bringing this up. I was listening not long ago to some Horowitz, Richter, and Gould live performances, and was just shocked and appalled at the noise the audience was making.
Yes, I know they're probably old and not in control of their bodies, general.
It is, in that respect, sort of just plain sad.
However, for those who -- and I'm sure there are more than a few -- lack self-restraint or concern for propriety, they're just entitled old farts, and I'm glad they're dead (on the recordings I heard, they certainly are).
ETA however, I've occasionally let loose some major (dry!) farts while practicing at home. Yes, that is also upsetting to me, and I generally like childish humor. I only shart while at the computer. And for that I am thankful.