Make them have to pass a Quiz or something like that.
And all new users will have to pass a quiz, not only scammers.
I'd also like to vouch for a 2 week registration lock
If you register you have to wait 2 weeks to make your first post
Would you register to forum where you need to wait 2 weeks to post something(as regular forum user)?
Also that won't solve anything because they would probably make hundred accounts.
The trust system seems to be fundamentally broken and doesn't help stop the scammers at all.
It's not broken. Why do you think it is?
Need a reputation system on top of this. Like 2000 Bitcointalk members -1 a user (scammer)'s reputation => account automatically locked, must contact admins to unfreeze
They will just move to next account. And this:
people would abuse the shit out of that to get the accounts of people they don't like locked.
Bad idea IMO.