Agree with Fisume. Some clans in the past attracted pretty bad members, the BDE are legend. The only clan composed of total asshats.
There are a rise of good clans though. So there' a good chance that if you show skill, you'll be invited to some. It doesn't hurt to ask either.
You can also start your own clan of same-skill-leveled people if you want. And then there are the federations which you can also join.
Point is, there are a lot. Just take note of the prefixes on names. There are old clans like the [BOT]s or the [MoN]s. There are elite clans like the -V-'s (I can hear their chests swelling up, LOL, but it's true, you guys rock!). There are also the admin/dev clans like the [prae]'s and the [X]'s(Not sure if you guys are dev clans though ;p so forgive me, but I do get that impression LOL).
As for the clan-standing thing, I actually will have to contact a member of a certain long-standing clan (the founders of which are old friends) because a recent new member and I got into an argument that ended in a kick... oh well, shows how you can't always choose the personalities of the people you let into your clans.