totally agree with you.If AppleCare+ can't distinguish OLED degradation and/or condensation from sticking a watch in the freezer then using express replacement might work once I get the battery down below 80% but I still don't think I want to take a chance on getting a repair bill. AppleCare+ is costing me $5/month so I can go a while and still pay less than $100 battery replacement fee.
there is something you could do though that might affect the displayed battery health (or not): let the watch run down until it shuts itself off, then charge to 100%, check health and repeat. when the chemistry in a battery is not fully used over time (eg always charging from 20% to 100% or so), there might be a "calibration" ...