Was interested in a used vehicle they had in stock...

Was interested in a used vehicle they had in stock. When it came time to work on a deal they demanded to check my credit before they would even talk about a deal. I then told the salesman that we would be purchasing on our line of credit rather then a dealership loan. He then proceeded to tell me it was the worst idea ever to do that and that I should defiantly use the dealership loan. The service was decent but unprofessional. They also were unwilling to move on their price of used. I'll purchase from wheaten gm from now on.