Str82u - 12:41 pm on Jul 3, 2012 (gmt 0)
@jemois, I think @Tedster answered the question, 301 can transfer good and bad rank from old domains.
I had a bunch of registered/reserved domains 301'd to the "main" website, in case someone looked up the domain they'd know who it was. After removing the redirects and letting them 404 or giving them a searchbox page, the "main" domain got better SERP and traffic.
Even more, you might have found real-world evidence that a domain level 301 can transfer a Penguin penalty.
Coincidence? I don't feel like it was, no more than when I removed a few hundred footer links in "satellite" sites to another domain and that increased in SERPs. The satellite domains, BTW, were registered in the same name as the "main" site.