Do you have an awful lot of sites linking to you with the nofollow attribute appended to the link? Are you worried Google uses that as a signal to not trust your site? Google's John Mueller said don't worry, it won't hurt you.
In a Google Webmaster Help thread, John Mueller of Google said having a lot of links with nofollows pointing to you won't have a negative impact on your site.
Having links (even a large number of them) with rel=nofollow pointing to your site does not negatively affect your site. We take these links out of our PageRank calculations, and out of our algorithms when they use links.
It obviously won't help you either but it shouldn't hurt.
I am a bit surprised by this, because if 90% of the links pointing to my site were nofollowed, I'd think that would raise a red flag. Of course, assuming I had a substantial number of links.
Forum discussion at Google Webmaster Help.