I agree with you on the smoking bit - but if they are doing it in their own home, it is very rude to go into their home (even if it is in their backyard) and tell them not to do it because you don't like it. I'm not going to go into it any further than that because we all know about how bad it is, but it is still their choice.

Anyway, I wouldn't expect you to say to Evan, 'no it's ok...' when he says something, but teaching him that there is a time and a place for things to be talked about would probably be a good idea if he's prone to doing things like that.