First post, but been reading over my spouses shoulder for years! We have a large number of sites that link to my site. We provide a small service to these sites in exchange for them linking back to us. It's been great for advertising and serps. In the past, it worked out great, but now my site seems to have a penalty. Serps have dropped way down. I'm thinking it may be possible that google is punishing us for having all those links. It's a little funny though, I can file a reinclusion request and the site bounces back up, then goes back down after a few weeks to a month. Is it possible to overcome a penalty by begging and buying high pr edu and org links? Or some other way? I'd rather find a way to overcome this rather than dump all these links.
Without knowing a great deal about your website, I would say if it is a typical marketing website, then its content will tend to be static and it will be indexed less frequently than something like the NY Times website. When you ask for reinclusion, you seem to be triggering an indexing event, which temporarily lifts your site in the rankings. But, without fresh, on-topic content being added frequently, it is not going to be revisited as often as more dynamic sites and it may start to drift lower. In my case, I have sites which Google seems to spider every week and sites which they hardly ever visit. If may be that the only way to combat this problem may be to initiate an AdWords campaign or look at advertising through one of Google's competitors, which might be cheaper.
The site gets cached about once a week (pr 6). I'm not sure how that is related to a penalty though. The site doesn't drift lower, after a few weeks it will crash with most serps going from top ten to disapearing from the kw tracker. Overall though, I'm trying to figure out if a penalty can be overcome? If one gets a penalty from incoming links (ok, but google says that doesn't happen?) can the site get out of the penalty with further/better seo without dumping the links?
My site ranks page 7 in google. then slowly drops to page 13, and finally disappears. Two weeks later, it shows up again, but keep dropping again. Have no idea for that.