A few years ago I bought a chart from Ebay of a Tiger Lazing on a tree. It looked amazing but I didn't get around to stitching it straight away so it was put in my stash until this year. I made really good progress on it and it wasn't until I was about half way through the actual tiger that I noticed a huge difference in colour from the picture that came with the chart. So I double checked it and I was using the correct DMC shades.
I just think the person who converted the picture wasn't using very good software and the problem with buying from Ebay is even if I had stitched this straight away after purchase, it still would have taken a couple of months so therefore there is no way of complaining about it.
I'm not saying that everyone who sells charts on Ebay are bad, far from it, I have had many that have been brilliant but just be cautious.