As I am reading threads this morning, I've come across a few concerning being outed by photos on their phones seen by someone else or sent by accident from their phones.
The solution seems simple to me - don't have pictures of yourself all dolled up on your phone. If you don't have these photos, nobody can borrow your phone and see them and you can't accidentally send them to someone. Make sense?
Personally, I have hundreds of photos but they are on a password protected thumb drive that I keep hidden. I don't leave it in my computer. There are other ways to hide photos, yet have them available when you want them.
If you are "out" or want to be out, keeping photos on the phone is fine. Otherwise, get them off.