Assuming you are using the Taylor R0013 reagent system, no cloudiness = no CYA. So far as I know, the R0013 does not deteriorate.

However, if your pool water is clear, it's easy to verify this: just add a couple of gallons of bleach early AM on what is to be a fully sunny day. Test an hour later, and again at the day's end. If there is CYA, there will still be quite a bit of chlorine left. If there is no CYA, the chlorine will have almost completely disappeared.