Well maybe if we make sure that no one ever replies or buys anything from the spammers...

Or we could just IP block the spam sources...

Or we could check for keywords on tweets that could be spam....

Or we could stick in one of those text boxes to be really sure its a person not a bot....

Hmm. Never mind.

Yeah i think you might be on to something.

Aside from spefically letting people follow you i cant see a general one size fits all solution to the problem.