The only time I was "caught" was when I was camping. I was wearing nothing, but a shirt and a thick diaper. Someone came around trying to sell something and they saw my diaper.
I also wore a diaper to the beach and it was showing under my bikini bottoms. I'm sure everyone saw it, but nobody said anything. When I put my swimsuit on, I knew people were going to see it, so it didn't bother me.