I could be wrong, but I don’t really think that Google is in the business of censoring their search results, except in rather extreme cases. Moreover, they don’t handpick the images or websites that show up in their results–they use an algorithm. If something is in the Google results, it’s because that something is on the Internet.
That said, you can report images as offensive. But my understanding of how this process works is that they will use this data to further develop their SafeSearch filter (which only works if you have it turned on, by the way). It does not mean they will remove those images from the search results.
This post on the GoogleSystem blog explains how to report images if you want to: googlesystem.blogspot.com/2009/07/report-offensive-google-images-results.html
However, if you’re really that offended by seeing this stuff, why don’t you just set your SafeSearch settings to “strict”? That should filter out most of the stuff that would be considered objectionable.
Edit: I also found this: images.google.com/support/bin/answer.py?hl=en&answer=112750 On that website, you can find a link to request that websites be removed from their search results. Let me know if you have any success with this. I’d be interested in learning about what type of criteria something has to meet in order for Google to declare it “too offensive for the Internet.” I say that because there’s a lot of really offensive stuff on the Internet that Google seems to deem completely acceptable.