A better solution to stop the spam would be not allow new registrations from an existing IP. But even that has some limitations, as there can always be multiple people using the same IP. Disabling registrations through TOR, and checking cookies could be another solution.
i think this policy it is already in use...
if you register with tor,
bitcoin talk ask you money to enable the registered user...
if i find the thread again i post here....
No, you are wrong. The registration through TOR is not disabled, the fee that you will pay if you'll register through tor it's only to enable the "post" function (not for nothing else). More info at: https://bitcointalksearch.org/topic/m.8044683