I think many people understand today that the photos they put on Facebook and other social networking sites can be used against them by employers when searching for a new job. I'm sure a lot of people posting pictures to Facebook have thought better of it after a few hours, days, or weeks and then went back and deleted the photo. The catch is that the photo may be deleted from your profile and as it turns out, often the photos are still the Facebook servers and accessible.
According to ArsTechnica, three years after photos were deleted from some Facebook accounts; the photos are still accessible via direct links it has access to. All a person needs to be an access the photos you deleted in most cases is the direct link to the photo, and you can still see it. ArsTechnica reports that it started following this back in 2009 and that some of the links to deleted photos they found still accessible back in 2009 are still accessible today despite being deleted from the user account.
The interesting part of this is that Facebook has in the past said it is working with its content delivery network to ensure the timely deletion of photographs. Facebook maintains that its goal is to see the photographs are deleted within 45 days of receiving a request to delete the photo. A Facebook spokesperson claims that the new system for deleting photos is close to being complete and only a small number of photos that were requested to be deleted are still available. If you have any direct links to photos you deleted on Facebook, check them out and see if they're still available.