" I've had the finance guy literally not shaking my hand at the end of the deal and telling me never to buy a car there again"
That's a very, very common scam. The "Finance Guy" (or the Sales Guy's Manager) - saying never come back again. Sometimes they'll even say how they screwed up, and lost money on this deal. Sometimes they say they may have to sue to get some money back...
It's all an absolute complete scam. Car Dealers have been doing this for 50+ years, and they pass down the techniques and drama to new sales teams. They will never, ever do a deal that they aren't completely happy with.
And the "mistakes" (also a super common technique) are almost always placed on the deal so that the person buying the car takes away satisfaction at having "fixed" tiny parts of the deal.
My cousin was a car dealer, and, while I love her to pieces, when she started talking about her job and their attitudes towards customers ("Buyers are liars"), I absolutely understood how just filling a role can change how you fundamentally behave (see: http://en.wikipedia.org/wiki/Stanford_prison_experiment for more details)
Your last scenario, btw - is actually the exact way to buy a vehicle from these jerks. Do the research, find the absolute best price, end of month/quarter/year dealer incentives included, and then find a dealer that's rated well for service - and give them a Yes/No offer, all in (including shipping, transfer, paperwork, whatever the hell they want to make up - you don't care, just as long as the bottom line is less than your number) - and a time limit. If they can't do the deal within the time limit, no drama or discussion, just go to dealer #2.