Sgt_Kickaxe - 2:14 am on Dec 3, 2012 (gmt 0)
But for merely a site that could be considered "thin", I don't think it can harm your whole portfolio.
I don't think a few thin pages on one site will hurt your other sites but what do I know, it's possible. I sold a site recently to focus my efforts on one so if Google continues to link them together then my remaining site is at the mercy of another owner. I don't think that aliasing sites would be a good way to build search result pages.