Since April 2011 Google image has not been as it once was, thats be cause they combine web results more close to the image results, which have really hurt the image search. Today I added my daily search celebrity to see the results and I have NEVER seen such bad results since google image started, first page had images of the celebrity, then it all got mixed up with all kind of images and I used a 4 word phrase. I dont think that many webmasters care so much about Google image anymore be cause they have this lighbox system so the user dont get to original site, I also recommend to block google image, but im still interested how they rank images.
I challenge anybody to find images of an eclipse that happens at twilight.
I lol'd at that one. Unless you're into astronomy and Google knows it you can't find a picture that doesn't have a barely clothed vampire or werewolf in the bunch. Yahoo! and Bing both have better image results, you're right. Actually I see Google results suggesting I want to buy the book on Amazon or ebay even. No thanks.
I have now notice the search I usually make is now back to normal quality, maybe it was a glitch in the system. Still I think the image results has gotten worse after Panda, be cause they take there web search results more into the image ranking.
No, I can not confirm this. Of course there are a lot of really (!) spammy hotlink-farms - and Google said that they want to rank images with high quality (text-) content on the target-page better. But until now I couldn't see that this works. But this is since years a major problem. I would not say that i gets worser ;-)
In Germany we have a cool "image search index tool" (not my project). It's for free (called "bidox") (You could open the site with a .de at the end). This tool shows that neither Panda nor Penguin has any influence to the image search results.