I agree with most of what both TJMadhouse and Andrea J have said...and stand by what I've said as well. We're not in conflict, there are just a lot of variables.
In quick summary....it all comes down to what's been installed and, more importantly, how it's operated. If the chlorine level is adequate and filter is run long enough to keep the appearance up...it's generally OK. Unless its a cloudy wading pool, I'm swimming!
As for hot tubs....small volume...high temperatures...yeah, it can be ugly. Chemicals don't hang around as long when it's hot. Bacteria love the temperature around 98.6 degrees. Want to guess why? Think about where they've come from!