I have pricelined and stayed in over 50 hotels. To avoid getting the worst room, I signed up for every frequent hotel stay club and called ahead of time on my reservation to put my hotel # down. Since I have doen this (30 hotels) I have not once got an undesirable room. In fact with the number loaded in I always ask for non-smoking king and a 'higher up' room and receive this with no objection.
I suggest you sign up for the rewards company (Marriott Rewards for Rennaisance) and you will not get an undesireable room.