Just a note to flickr account holders (this means you too, Mom): You’ll likely want to go into your account settings and change your search options. Apparently flickr is doing a little something regarding moderation of search results and age appropriate content, so if you want uncensored search results then you’ll need to change the new default setting. This setting does not only mean that you could potentially filter out (or include) potentially offensive photos, but also art, illustrations, and screenshots as well.
You’ll want to go to You > Your Account > Privacy & Permissions > SafeSearch settings
From that point, you’re on your own. I have set my account to SafeSearch off and I am including all types of content. You may not want computer screenshots included, but I do.
A bunch of the categorisation appears to be voluntary, meaning that the uploader is largely responsible for classifying his content or retro-classifying what is already up there. I’m sure there will be huge discrepancies as some users have thousands of photos uploaded and who has time to filter through and reclassify…
Regardless, if you want art, illustrations, adult content (which I assume includes any form of artistic nudity or disturbing imagery), or computer generated or captured images included in your flickr search results, you need to make some changes to your settings.