There is really no full-proof way of stopping useless threads , its simply a problem with forums which has no ready solution , though i think i agree with the first person who sees a useless topic should say so and no one else posts in it.
I have to admit some people just amaze me with idiocy at times (most of the locked threads) where i probably would of replied with something vicious (i cant help it) , but i think people should just get IP banned or something so they cant make a new email adress and register again.
There have been a few spammers recently who are probably all banned by now , which has been anoying , though i dont actually care really.
I think some people do need a little more tolerance of spammers , don't go berserko on them since its useless , and they are generally dim witted idiots who don't know how to speak there own language.