Here's an example of a good dealer interaction.
When I was looking for a pre-amp, compatibility and good results with my existing phono rig was a consideration. I was interested in the ARC sp16 that I ended up buying, but wanted to make sure the phono section was up to snuff. The problem was the sp16 phono input sensitivity versus the low output level of the Denon DL103R cart, which I did not want to have to change.
So the dealer ( a very small home audio shop in Baltimore area) let me bring my Linn with DL103R in and give it a try. As expected, not enough volume was possible. When I insisted that this was a problem, he offered to let me try and buy a used Electrocompaniet step up device from an associate of his (he was NOT an Electrocompaniet dealer and the unit was not a current model anyhow). So I did the audition again with the Electrocopaniet and bingo, so I bought the ARC and got a good deal with the Electrocompaniet.
I had to know to stand my ground on the input sensitivity issue but once I did the dealer did what he needed to do to make things work and make the sale.