The wiki sates the rules about clans something like this
Don't use your clan to ruin other people fun.
If you suspect people are using a OOC clan to "win" the game the best advice is report it to the titan and let them use their tools to investigate. Its a hard thing though, it is quite legitimate for a group of noble characters to act in the way you describe, I guess the problem is when they do it for OOC reasons and friendships rather then developing a IG dissident group.
