We are very lenient on moderation and most topics are okay, but if we see that someone is going out of their ways to upset others we take appropriate action. Fortunately, we haven't had any major issues and we only have a few on our ban list, all for harassing members of the clan.
We log these bans on our owner spreadsheet.
A tip from me is that you should figure out what kind of clan you want. What is okay, and what isn't. You probably have a set of rules, but do you enforce them? Remember, those joining and staying in your clan does that because they like the climate that the leaders has created and it's important to maintain that as you grow.