actually that more tends to come from the booze and other 'substances'. also perhaps the way they are sometimes treated any more. i have known old, and even very old, people who weren't that way at all.
Bad people is a really broad classification. I might act and tolerate different depending on how or why they are bad. I might be more accepting of someone else doing the same bad stuff as someone I have a hard time tolerating just because I have a click with that person/like his personality better. And sometimes I might act different just because they bothered me at the wrong moment We're all human. Having no tolerance for people just because someone is in politics, or in the teaching or accountancy business is ludicrous and bordering on insanity.
yes, alcohol in paricular, see i more and more with heavy drinkers as he get older, get confused and frustrated easier
a lot of it comes down to whether i think the person is a decent person and is respectful to me or not. i have a low tolerance for people that will steal from you behind your back. i don't care too much what people do that i'm not involved in but obviously some things cross the line.