Always dehydrated: only occasionally hospitalized for it.
Pinch Test:
Pinch up the skin on the back of your hand between your thumb and pointer.
If you are well hydrated it will pop right back down flat after you pinch it up. If you are "down-a-quart" it will fall rather slowly.
I learned this from an ER nurse.
Is there more to the story? Why, Yes, yes there is.