I had problems with the search engines on my old site. I had released a couple themes, and a plugin. Lots of people downloaded them, and used them which is fine, and I got some free incoming links. But many of the sites using my themes and plugin were spam sites. And they all had links back to my site. Apparently the search engines saw these links as evidence that my site was a spam site, and it tanked in the search engine results. So I moved my site, and removed the theme and plugin pages.