It uses Google's safe search, so the images would be found in a browser search as well. I think Google may have a tough time keeping things "safe".
Yeah. I remember when it happened, that I pulled up Google, enabled Safe Search (which I normally keep turned off), and tried a few searches and got similar results. So I wasn't blaming you guys.
Also, while not porn, you do get some amusing and sometimes disturbing results with oddly named Artists.
Bright Eyes, for example, ends up pulling up quite a few pictures of teenage girls (with their eyes wide open). Mildly disconcerting.
Of Montreal pulls up lots of cool pictures of Montreal, including a few old blueprints of buildings and churches in the city (which is cool).
EDIT: I was looking, because I was curious, and I just found one that'll do it. [Artist] = Girls (which is a band). They're not all strictly hardcore "porn" but many of them are certainly NSFW.