I have always suppoerted the idea of a Bad Client database. However, two points:
1. It is so easy to change SIM-card nowadays (Tesco give a free SIM with the purchase of call-credit!) that one wonders whether a seriously dangerous individual could be flagged this way (as opposed to drunks, time-wasters and eejits);
2. Posting details of the SMS scheme and then deleting them could cause upset and fear among clients who were stung by "The List". Better not to have this thread than to leave it to chance whether a member sees the details or not.
Just my thoughts on the matter - but, as I said, I have always supported a Bad Clients listing.