Most people are not concerned with PR, their status in life does not require them to have a huge interest in public relations. Then along came social networking, where you put you image and life on the internet. Your friends can check on your status, see photos of your kids, or even remember old college pictures. This can discrediting to some depending on the nature.
Depending on who you allow to see you info, along with being able to have a private profile. Social networking sites have tried to keep up with the trends over the years. Although they have thwarted many attempts of phishing for info, it still goes on today.
A teacher could get fired for an old college picture with to much of her breast showing or drinking perhaps. Just because she had a picture on her profile on a social networking site from her college days. You have to be careful of the media you allow yourself to put on the internet. If not it could land you in a rough position one day.
I myself had tons of photos that are not the most professional. Yet it defines who I am. It is a moment captured in my life, regardless of the act at hand. Unless it is of a violent or criminal act. I would consider porn because in some instances it could have a positive affect on the outcome.