During my recent stays at the Contemporary my family and I stopped taking the bus to Downtown Disney because we got tired of always waiting for it to arrive both going there and going back, so instead we took our car which is a lot faster. Plus their bus also shares with the Polynesian and sometimes the Grand Floridian, so there would be guests on who were staying at those resorts and you couldn't tell who was staying offsite and using it just to arrive at the Magic Kingdom.
Personally I found it to be more frustrating when a lot of the offsite guests would be getting on the Resort Monorail going to the Transportation & Ticket Center after having dinner at the Contemporary, because there have been a lot of times when it caused long line ups and meant waiting for two or three Resort Monorail's to arrive until we could get on. Now incase you or anyone else asks how did I know they were getting off at the TTC, I would always see a lot of guests who got off and started walking down the ramp. However I will say maybe some of them were also getting on the Epcot Monorail.