You might be right, but how would you know for sure? Maybe two identical games, one with crude bit-mapped cover art and one with polished cover art and see which one gets the most hits.
That's a really good idea - I think thumbnail is a huge part. It's honestly, really honestly, why I put the pixel image of the main character on it, instead of just the title. Anime-style girls catch the eye for a lot of folk, even with a very low pixel count!
