So we have been manually banning by and delete accounts that just spam the forums with ads, but there has to be a better way for this. If anyone knows a better solution please let me know.

i dont really know but maybe some sort of Capcha

?

I think you can just disable the ability for people to make a new account and have immediate access. You just will need to have a step where you personally have to approve each new account before it is established with posting privileges. That would be a pain if there were tons of new people coming to these forums on a daily basis but I think it wouldn't be that difficult currently.

Thank you for your suggestions. Some steps we took so far are:

-Enabled "Check IP against DNS Blackhole List"
-For those that do get through, a manual IP ban is issued and account/post deletion right after
-Increased CAPTCHA difficulty for new registrants, may be harder to read for actual people too.

Seems to have less ad spam now...