Simple question about DP Coop and Google: does it have a known negative side-effect on PR and SERPs to use Coop? Could it even lead to penalties?
I can't say for sure, but I think being part of the co-op kicked one of my sites (7 year old site) into the sandbox. The coop worked really well for quite a while and help me get ranked well but at the end of May things started taking a major tumble and finally dropped for good in August for my main targeted word. I have removed the coop from the site, and am waiting to see if google will allow me to dig myself back out.
No. It does not have a known negative side effect. I have been with the coop from the beginning and have seen no negative effects from it. Although, people will blame the coop all day long if their sites rankings drop . You'll see plenty of arguements about it here: http://forums.digitalpoint.com/forumdisplay.php?f=34
When I added Coop to my site, I was banned from Google for excessive link building - and when I removed it, they allowed me back in again. I would call that a negative side effect personally.
So Google told you why they banned you? If you were banned for "excessive link building", that is not the same as being banned for using the coop. What is your website?
Why not work for quality link building instead of quantity link building? or using TLA for text links