We avoid the ship's photogs as much as possible. If they do take the pic we don't buy it. In the dining room we have the waiter take our pic on one of the formal nights. The waiters' pics usually look better than the pro's. One night we were going down the fancy stairs on formal night and asked a passing staff member to take our pic. It turned out great!
I will say Celeb's photogs are not very pushy. We just slipped around the people in front of us at all our ports on our recent MR cruise. No time for pics anyway as the excursions were leaving.