Just a word of warning, I got nailed with about 120 rejections from retaildata, even though I followed directions. Last time I did some of their HITs, all were approved no problem. Messaged them, no response so far.
I'm sorry, I haven't really been on the forum or mturk - recently hired for a full time position after being unemployed for a few months I did receive a reply - they clarified what it was they were looking for and reversed half the rejections