Obviously, the best way to deal with suspected merit abuse coming from a merit source is to bring it to theymos' attention rather than add a comment to the person's trust page. The post Theymos made was in a reputation thread with someone disagreeing with the way QuestionAuthority was handing out merits. I responded with some insecure paranoia that I would start getting red trust simply because people don't agree with how I hand out merits. In the end, QuestionAuthority ended up having his merit source status stripped from him.  
  Also, theymos did make a comment somewhere that he has the power to reverse merit transactions, if need be.