I don't mind when people fake it honestly. It kinda goes back to that saying of "if you have nothing nice to say, then don't say anything at all", so maybe the people should just keep quiet at that point...not entirely sure though.

I definitely agree with you that people should always be nice and friendly in formal setting, the problem with those people being nice in informal settings is usually the fact that you can't help but be around them in the informal. One of my best friends is friends with someone that doesn't care for me much, but I end up being around him so much when we go out for drinks and what not.