I sealed the heck out of mine (bathroom installation) with a "20yr sealer" and yes, I get darker wet marks all the time, also a dull haze on the rim over the sink by the faucet.

Is the dull haze from too much sealer or too much water at that spot?

dark spots from wet are normal even on sealed granite. the haze is typically minerals left behind by the evaporating water. a little rubbing with 00 or 000 steel wool will remove mineral deposits without hurting the granite. (do not use steel wool on marble.)

Good to know oldryder. But if water makes a ring, what would a glass of grape juice do if the juice ran down the side?