When I was using co-op I was warned by a few users to keep the number of links down because large number of inbound links can get google to penalise your site as Matt Cutt said on his blog once that they are cracking down and penalising on sites using co-op to unnaturally build up back links.

coop is a very unnatural way to get backlinks. I can't prove it, but I feel that it really hurt one of my forums. Haven't used it in several months but things havent improved. I just recently submitted a reinclusion request, hoping to get some better results.

If I don't see any difference withing the next 6-8 months, then I guess it isn't coop. If I do, I can only assume that was the reason.

I haven't used Co-op since about the beginning of 2006 myself. It never really helped me.

The value of COOP pretty much died toward the end of 2005, at least for me.