23Sha-ger The spam is being posted using real browsers with JavaScript support whether it's done by bots or humans. Most of the spam which gets through is also very clearly being done by humans, not bots. The only thing which works for a while is banning the IPs for registration. We participate in a cross-forum system for banning them:
https://www.stopforumspam.com/
The recent spam appears to be specifically targeted to this forum and therefore the IPs haven't already been added to the registration IP ban lists we obtain from Stop Forum Spam.