I had only one patient who recorded everything. It didn't bother me b/c he had legitimate memory problems and these recorded visits were helpful for him. I have one other patient who wants the printed office note at the end of every visit. That doesn't bother me either. But I am careful not to record observations in her care that would be misconstrued as offensive to her.
I share the concern others have about the legal implications of a patient having added ammunition in the event of a law suit. But I always try to stay professional with patients, so whether they have a recorder in a handbag or laying out on the table it's the same either way.