Is there a definite way to know? I had a site a few months back which was picking up rank and even reached first position and stayed there for a couple of days before losing rank. Maybe that happened cause I stopped SEOing for it or maybe I stopped putting up new content on it or maybe G penalized it. I want to rebuild it but I want to know for sure that the site wasn't penalized cause I don't want to work on it again only to have it all wasted. So, is there any way to know?