I work in IT, doing what's called data mining. Which is looking for relevant information in piles of data, most of which isn't interesting to you, and trying to separate the wheat from the chaff. One day, I decided to try and find out as much as I could about some of my favourite porn stars. I was a little shocked at the ease with which I could find their real names, details of their family, and sometimes even home address and phone number. All it takes is some carefully crafted Google searches to get started. Social media helps massively here. Once you find one girl, she's often facebook friends with a bunch of other girls that she's worked with, so you can get information quite easily via that route. The system's only as good as the weakest link, and some of the links are very weak indeed.