I think with everyone it's just one of those things you start out worried about but over time you get more and more used to it until it just isn't worth worrying about anymore.
I've been 24/7 for several years now, and I've gotten so used to wearing diapers that the only time I "feel weird" is on the very rare occasions when I'm NOT wearing diapers. I might stop to tuck in my shirt or something but that's about it. I don't have a panic attack over it, and if someone saw me, owell, they'll either say something or keep it to themselves. I know for a fact that I've been discovered on at least a couple of occasions, and have never heard a word from them about it, so at least in my environment people are mature about privacy. YMMV there though, if you're in say high school I think playing highly defensive would be recommended because of the lower level of maturity you're surrounded by.
I will however argue against the "no one can hear you or see anything". It does happen to me from time to time. I have vivid memory of some years ago being 15 minutes from close and finding myself in a pretty soaked teddy when an old customer walked in. He noticed my slight waddle (due to a lot of sap bulk between my legs) and asked if I had something wrong with my gait, "you look like you're wakling a little funny, did your leg fall asleep?" "YEP! I've been sitting all day!" (I wasn't going to refuse the "easy out" he just threw out at me)
Twice I've had my crinkle questioned, and both times I've explained it away by tapping the front of my pocket (which is right in front of the side wing of my diaper, which immediately let out an audible crinkle in response to the taps) and simply saying "candy wrappers". (thankfully neither asked if they could have some!)
I don't think it's a good idea to tell people it's never going to happen. Maybe for some of you it never has, or no one has said anything to you about what they've heard or seen, but at least in my experience, it does happen occasionally. Just take it in stride and move on.