For me, I just try to stick to a general rule of realizing that other peoples feelings can be affected by basically anything a person can say. Affected in all sorts of ways because that's how words an ideas transmitted verbally work. I've overstepped the mark countless times I might add. But when I meet people for the first time, I just keep it light and not overpower them with heavy thoughts and ideas, ideas I know they might find distasteful or even offensive, because I just think it's respectful to observe their feelings. After all, 9 times out of 10, they're going out of their way to be nice as well. But as I say, I've overstepped the mark many times, especially when I was younger. Now, I think there's a time and place for everything.
So, that's it. If they want to turn around and flee, then that's fine. It's who they are. I prefer few people in my life anyway.
But there's the other similar saying to Breaking Dawn's one, too, which is: If in doubt say nowt.