Like johngw, I've never been "caught" because my thonging has been at bars, beaches or pools where I deliberately wore it in public. I'm not much for thong underwear, so it wouldn't show up in a plumber's crack. They're great barwear on jockstrap night or on beaches where they're allowed.
If I'm just wearing a thong or a string in a public area it's because it's an area I'm comfortable being seen in it so 'caught' is perhaps not the right term. A possible exception may be encountering law enforcement who decide to interact with me over what I'm wearing but that intersection hasn't happened. If I've worn a thong or string I haven't encountered them and if I've encountered them (or close, as for a recent situation where I was wearing just my brief Skinz Sunseeker and a cap on the footpath as a police vehicle drove past). Were they to ask I'd ask about the Summary Offenses Act and how I don't meet it.
For me, 'caught' would mean being seen nude by a textile when I thought I wouldn't. I tend to take care and the few occasions haven't been an issue.
Great set of photos, John. Sheer fabrics are one area that's a little grey for me in terms of whether it falls on the 'nude' or 'covered' side. Certainly I haven't worn anything quite as sheer as some of yours as something that makes me feel legally covered.
I wonder if anyone has experience of where the acceptable boundary lies?
In my case it was more deliberate. It was the first time I had ever worn a thong to a public textile beach and took it cautiously at first. I sat in my chair for a few minutes without so much as removing my shirt just to observe. There were no other thongs being worn by anyone and that in a way made what I was about to do more exciting. I removed my shirt and dropped my shorts and stood there for several moments looking over the water while on full display. At that moment it was every bit as liberating as my nude beach experiences. As I stood there I discreetly snapped a few selfies using the remote on my watch. I didn't notice at the time, but in the one photo attached there was a guy in the background staring at me. Fun stuff!
I stretched out on a towel tanning my ass as a number of people walked by without issue. The confidence I gained on this day led me to return the following day, although on that day I would return wearing my more sparse g-string. The g-string also brought with it a heightened arousal that required some consideration!
As I have said before I have never been "caught" but the first time I wore a thong in public was back in the 1990's when I had been bathing on a nudist beach and my wife asked me to get some ice-creams from the beach caf. As nudity was not allowed in the caf I put on my underwear thong to make the purchase.
When we walked back to the apartment I didn't put my shorts on but walked home in t-shirt and thong (I didn't go commando much in those days). My wife complained that from behind it looked as though I was naked under my t-shirt.