LOL, yeah being a nurse doesn't help much with fish, I'm getting this image of a nurse taking a fishes pulse
You wont know the difference until you see one in shock to compare it to. Sometimes they really seem dead. At the warehouse we always started acclimation unless they weren't in one piece or had obvious rigor mortis. We took it to the point of about 15 minutes after we added our water to their bag to even try to decide. I've put 500 chromis in a tank that all just sank to the bottom all curled up and not breathing and came in the next day and they've looked great.