In the good old days (10+ years ago) you could negotiate an extra tip with the girls to get their picture taken. I got more than a dozen of the beautiful legendary "old timers" on file. That all ended as the cameras got better, video was available, and more stuff got posted on the Internet. It is impossible to get them to agree to a pic now, at any price. Taking their pic without consent is WRONG if not illegal in this state.
Sneaking a pic/video is a perverted act--you need professional help.