I've only ever worn one in a pool that's in an secluded area of the gym and mostly hidden from the gym area with no lifeguard and when it's very quiet on a weekend morning. Back then I had a cover up and only took it off once in the water and then quickly back on after someone had come in as well.
I'm going be getting back to the pool soon and will start wearing my thong suits and won't try to sneak around and just go regardless without worrying about being seen. And hopefully to other pools which are more visible from other areas and with people and lifeguards. I'll get back with updates as I get the chance.
