Thanks, it has mayday penalty. May 2010. It had adsense at that time. It was Google's idea to move adsense up. Adsense remained there for about one more year after the ranking penalty, and then adsense ban. No explanation. So we suspect it is not about updates, it is manual penalty, just to make trulia and zillow king. this is why we didn't work very hard to find and fix a problem, because penalty came when we didn't make any change. it is possible that we got better rankings than deserved in early days, but now we don't deserve such big penalty. Hiding text, link buying,... nothing like this. trulia and zillow takes mls data and other data from different sources and they are considered original content and not duplicate of anything. They may be useful, very useful; but it looks like they are a little bit artificially promoted: rankings given manually. if they buy links, hide text, will they get penalty? I don't think so.