Now we are looking for solutions like no more signatures until someone has 5-10 posts. What do you think?
I think this is a good idea. I personally have been encouraged to actually participate in a forum in order to achieve the signature link ability and do respect those requirements.

...as long as our advice is good, maybe non-bots will benefit down the road ;-)
If they are not posting relevant material then they are just as unnecessary as the spambots but if they are and we are able to offer some suggestions - maybe we can help other "real" people later.

I'll participate with what I know - if you all will!