I reported some images to them, not due to the poor quality (blurred images probably taken with a cell phone) but due to copyright infringement (those were images of t-shirts with designs on them). I have decided to skip them. If I could only remember who referred me to them years ago (not from here), I could know if they are worth the trouble. The good thing about that is that you can upload a watermarked image for display, and an unwatermarked one that will be used for print. This makes them the only printing site I know with a decent watermark policy. Others have useless watermarks with large previews.
I don't think most of these sites do any inspection of the submitted images, though, I never had to wait to have imges online. Artists Rising does (probably worried about copyright infringements). Zazzle does for stamps, because the agreement with the US Post requires so.