I haven't had an excessive number of opportunities but I've done it ccasionally in ones that are not officially nude once in the water. No one else knows until the bubbles stop and I wasn't expecting anyone else to join while the bubbles were coming... :-D
The only hot tub I've been in during the last many years is at a men's-only clothing-optional resort. I'm nude the entire time I'm there -- including in the hot tub. No bubbles there -- just hot tub.
Oh, wait. Just remembered.
There is a jacuzzi at the gym. It's next to the pool. I almost never use it because it's clothing required. But once or twice (on the rare occasions that I've used it), I have pulled my swim trunks down and pulled one leg completely out of them -- leaving them around one ankle/shin. Easy enough to quickly get them back on if someone were to come into the pool area.
Used to go to the YMCA in another city. The jacuzzi was out in an open area. I pulled my swim trunks down to my ankles a few times. Made a point of keeping an eye on the timer and pulling my trunks back up before it turned off.
Of course, we do. It's absolutely normal here in public saunas. Women and men meet naked in the Hot tub.
I absolutely agree. It's uncomfortable to swim in swimwear but for the warm and bubble water it's completely the wrong material. There is nothing better than our skin.