If there isn't a designated lane to follow to valet parking @ Contemporary, I could see why the guards still want to know if you actually have an ADR. Some trying to 'game' the cost of parking would SAY they plan to valet park and then just park in the regular lot for free once past the guard shack. Clearly valet is MORE expensive then the cost of regular MK parking, but Disney has gotten wise to those who think they can park for free at a hotel and then walk to the park as a way to avoid paying for parking.