Hi Georg,

Looks like a penalty. We have experienced similar things yesterday on a number of websites which we've been adopting overly-aggressive link building tactics and it is a result of a recent google update:

http://googlewebmastercentral.blogspot.com/2012/04/another-step-to-reward-high-quality.html

It is not a result of your onsite SEO. There might be different reasons for it but I do consider it as a result of article spinning which might have been taking part of your link building activities. Especially if the keywords that you lost rankings for have been targeted by such links - spinned content on private or public blog networks.

Have you had some kind of drop in rankings about a month ago for those particular keywords?

Kind regards,

Ivo

I think that such a practice can be quite good if you do it well and if you have a good product or site to be reviewed. You don't even need such platforms to do that. We call it Blogger outreach campaign:

1. Simply shortlist a few hundreds (or even less) of good blogs in the industry and market you want to focus on.

2. Think of a what offer you can give to them. Money most probably won't work. You can incentivise them with an affiliate offer or something really touchy and personal. Put that in your email to them or on their contact us forms or call them.

You will see that most of  the guys will reply and will be happy to cooperate. This works much better than any platform if you are going for the quality links not for the quantity.