Back in my black days I'd go around Clan Discussion giving the new clans an eye or two and I've seen some god-awful threads. It doesn't really matter at all though, as most bad clans get weeded out of the officiality process. In all honesty, I'm actually quite in favor of them, you'd be surprised with the amount of players that become hooked into the community because of such clans. I was one, RIP Death Reapers.
I think that clans should be whatever the clan wants to be. If a clan, say, Friends of the Earth, wanted to be just a mainly forum-going, social clan, then there's no point they shouldn't be. Having a group of friends to socialise with would be fun if you had a specific board for each group of friends to post in, but you can't, which is why you need a clan to do that. That's why there's so many clans. And I don't see why that's a bad thing.
Clans gave me a look into the forum and kept me there, honestly unofficial clans are mostly there to get groups of people together and stuff. I don't really see the problem in that.