Just received this Private Message from one of the Admins of MBWORLD:

Dear Rennteam

Your signature is in violation of our Acceptable Use Policy by containing Rennteam.com. Our terms, which you agreed to when you registered, state that unless you are a paying sponsor of our forums, you are not to advertise or solicit, in any way, your business or services. This includes but is not limited to contents of your post, your username, signature, etc. To review our Terms Of Use, please follow this link: http://forums.mbworld.org/forums/terms.php. We ask that you refrain from conducting business on MBWorld immediately. Further violations will result in your username being banned.

Should you wish to sponsor and advertise on MBWorld, please feel free to contact us at advertise@mbworld.org.

Thank you for your prompt attention in this matter.

MBWorld Admin

I asked for my account to be deleted.
Don't need to help them maintain traffic with somehow interesting posts and get insults from them as a "payment".

The funny part: most people posting there have direct links to their private websites in their posts (something I didn't).
Maybe they just felt threatened...
Money rules.