I must agree with Daniel and say that if you don't think certain threads are appropriate for your purposes, then simply delete them. There are plenty of other legitimate discussions on this listserv which prove our dedication to the profession.
However, I would politely ask that those responding to a formal topic with cocktail-party discussion material change the Subject line so that the not interested can delete them immediately.
Maria "I wish I was at SAA" Plonski :)