The personality of a forum is mainly based on interactions of users as a whole. The design and functionality of a forum is important as well, but that's the easy part. The harder part for managers of forums is keeping the posts on relevant and on topic, with users who have worthwhile things to say. I've never managed a forum before, but it doesn't take experience to accurately imagine what its like.
My request for better forum behavior is based on the endless number of posts which say junk like "cool list, thanks man" as well as people who use awful grammar, incorrect spelling, other vague responses like the example I just gave, and more.
One forum I use fairly often is Digital Point which currently has a page rank of 4, to my knowledge. I see a lot of half wits on this forum like what I described, and these people should be expunged from further use. The owners of digital point might want to ask me, "So do you have a forum or a website better than 4?" and my answer to that is, no.
Am I a nerd who is being a nitpick about a first world problem on a Saturday evening because I have nothing better to do? Basically. But it wouldn't hurt to enforce requirements that responses must be of certain length, and strikes against people who don't contribute well for the reasons which I described. Its better for the reputation of a forum to improve rather than go downhill or stay the same. This could be said about anything, but whatever.
I agree with most rules of forums which I've read, and a common one which I like is "No affiliate links!" No need to give spammers confidence in your forum. I'm an affiliate marketer myself but I'm not some overly promotional bastard who has no value to offer. No repeat threads should be a rule enforced more often, because too many topics get talked about to death.