Basically my opinion here would be... The complete opposite of something like gamefaqs. Be strict when it's needed (trolls, forum flooding, hate speech, personal attacks, overall constantly rude behavior, etc.), but not as strict on other things.
Gamefaqs lets the trolls run rampant while punishing people who report the trolls (seriously, a few weeks back I got my account temporarily suspended for marking people as trolls) or punishing people who do/say things that really aren't bad at all.
For example, swear words... yes I think it can be too much, and it's always bad when directed negatively towards other people, but when you can't say something like "this game is fucking fun", I think there's a problem
It has to be handled at a case by case basis IMO.
And yeah, I agree with jcalder, putting up a set of rules would be useful. No need to be super complicated, just an overall guideline.