I agree I have seen very few pools at hotels, etc. that I would consider swimming in, there are however a handful of places that I travelled to that have impressed me with their level of water care, at least on the non scientific testing method of lack of CC smell, water clarity, etc.
Perhaps this is a good time to make a list:
Starting with the waterparks
Schlitterbahn
The original water park in New Braunfels, Texas (I don't know about their new added location), one thing that makes them different than most water parks is they get their water from the spring fed river that runs next to the park and don't recycle it over and over again.
Atlantis Resort, the Bahamas
The effort they appear to go to on water filtration and treatment should be the envy of any pool operation, this may be related to the fact that they also have one of the worlds largest open top salt water aquarium setups.
The Greenbrier
The indoor pool at the Greenbrier resort is something everyone that is into swimming pools should experience, it is a massive Olympic sized Roman themed indoor pool, and perhaps most impressive of all is that it is over 100 years old. Perhaps part of the low CC smell and clear water I saw when I was there last summer could be attributed to the relatively low use the indoor pool saw compared to their outdoor pool. The few times I managed to get by the indoor pool during my stay I never saw more than half a dozen people using it, which is just the proverbial drop in a bucket in a pool of its size. (the ex secret nuclear fallout bunker for congress is impressive also)