Never talk about the failings of other people ...
Granted, we all like hearing a little gossip. We all like hearing a little news or gossip.
The problem is, we don't necessarily like - and we definitely don't respect the people who dish that dirt as we would not like it done to us.
Don't laugh at other people. When you do, the people around you wonder if you sometimes laugh at them. And note wisely try to never say nasty things to people - we never know what they are carrying around with them..