By far the worst I have ever seen was a model a freelance artiest sent to the company I worked for while making the film "Andalus". It was of a ship with oars and two main post with sails.
Now looking at screen grabs of it, it looked really good.
But when my boss paid for it and it was sent over it took me 4 days to sort it out. It was about 8,000,000 polys (way over budget) none of it labelled (never good sign) and had one very small texture. But it was the way the parts were layed out which shocked me the most. Random parts were grouped together (two of oar were grouped to a door and a mast) but it looked as if each face was a separate poly, which was a pain even more as it was all in tri`s and we needed poly`s. In the end I just remade the whole thing. We did try and get a refund but got no reply. But we did learn to ask for wire shots of everything else we got online.
Although not shown here on the site it was here we hired the guy from (naming no names)