In May, we talked about getting your images out of Google's SafeSearch filter. That is, Google may deem your images somewhat "questionable" (maybe lewd and lascivious) and won't list your images within the standard (SafeSearch-enabled) image search results.
We've been posed with the opposite question in Google Groups. One guy has a few questionable images but doesn't want all of his images being blacklisted just because of a few instances of questionable adult images. JohnMu suggests that if you have some images that are naughty and others that are nice, you could put the naughty ones in a separate directory or even allocate a separate subdomain to the other images. However, he also notes that it may be problematic to have adult-oriented images on the same domain as "safe" images. My guess is that this means that Google could still have a problem with it.
Forum discussion continues at Google Groups.