It was serious remark.
My brother have his own vbulletin forum.
His solution for spambots (as 99% of these post are generated by computers (bots) not human. Is the captcha (but some bots have cracked it) this will stop about 80% of them. (email chack is old news for bots)
then add some (not just one) Q&A's on registration (verry simple, like "Are you a robot or a human?" and "Do you use an impact wrench or an onion to tighten your wheels" or "Type here the blue text from our logo")
most bots are not able to logic these questions. This will eliminate 99% of the spammers.
Those who get past that are no longer bots, this are low payed human spammers (china, korean, malaysia, etc...)
They actual get 0.01ct for an ammount of hits on the link. hitting the link you could get malware, cookie trackers, troyans, etc...
The last check he have is the required introduce yourself topic. this have to be the first post and is moderated. so only get posted after mod or admin approve it.
introduction needs to be just a little more than; "hello i'm R2D2 and i love computer components" to get moderator apporoval by him.
Then once in a while he still have a spammer, but you can 100% be sure this is a person (no bot) that takes the time to fill in Q&A at registration, Did a good first introducing post and then starts spamming the forum.
These users you "perma ban" as bull describes.
also install VSa - advanced permissions based on post count
this will eliminate registering people that only post in classfieds or only spam people by PM or mail.
like min. 10 posts on the forum before you can post in for sale sub forum.
Every month he delete the accounts that made no posts (these are most likely sleeping spammers, that get in and wait for new bugs in vbulletin software to be discovered)