I think most of the time people can stop it simply by putting their opinion into the scam threads as they come across them.

We all have verbose opinions and love to type. 

If most people took a few seconds to identify the scam thread as they incidentally come across them by posting so in them, those threads would quickly fill with scam warnings.

Then we will have done all we can to protect our own reputations, because the scammers naturally try to mascarade as us, the non-scammers, and affect the reputation of this whole forum.