At least for image search, I use a Firefox extension called Unpinterested. I'm very happy with my search results now. Note: I had to toggle an option to make it work only for image search, because it borked other Google results.
I remember when Google added a functionality to block domains entirely from your results. They removed it soon after though; I'm guessing some big advertiser was blacklisted many times.
I remember when Google added a functionality to block domains entirely from your results. They removed it soon after though; I'm guessing some big advertiser was blacklisted many times.