I know the feeling. Motorway the dealer I went to simply quickly walked round the car. quick sat inside it. Got out and said "are you happy with the quoted price?" Then said "ok lets get the paperwork done." I felt guilty and even started pointed some of the faults out." We'll prep it before sale anyway" So i went inside. A minute maybe two of keyboard tapping later for DVLA transfer and bank details in and I was out the door with actually in shock and now car less. Standing outside the dealer thinking what just happened, I had to go back in to ask were nearest bus stop was as wasnt expecting to be car less. Lol. I got what the website quoted which was more than trade price and nearly what autotrader said private was. They had it up for sale a week or so later for just over a grand more then they gave me.
I guess it all depends what dealer and what salesman they send you too but I know I would use these again unlike they others I tried.