The worst I have dealt with was Tony Graham Toyota in Ottawa.
I was recently in the need for a minivan and was doing tons of research (including following the still on-going Minivan Challenge

) and narrowed down my needs: it had to have leather, power sliding doors, power tailgate, and movable 2nd row seats to allow greater side access to the back. This narrowed the field down to the Toyota Sienna and Honda Odyssey. I also had a mental ceiling of $40k before taxes and financing. Unfortunately, that took the Honda Odyssey out of the running as only the Touring model at $48k met the need.
Anyways, now having narrowed it down to the Toyota Sienna, time to go see it in person, try it out, make an offer.
I arrive at Tony Graham at 12:00 noon on a Thursday. Sorry, all sales reps are on their lunch break. Odd but ok, can I make an appointment for 6:00 p.m. then. I want to take a look at a Toyota Sienna LE with "C Package".
Show up at 6:00 p.m., sorry, all of our 08 Sienna's are locked up in the body shop for the night, would an 07 CE be ok? No, I want to drive the car I might buy. Can we book an appointment for the next day at noon? During the salesman lunch hour? Ok, guess they can do that

12:00 noon the next day. Sorry, we don't have any 08 Sienna's with leather. Would you like to see an 08 with fabric just to get a feel? I said "a feel for what? How good the leather quality is?"
Anyways, said they could have one shipped from T.O. if I leave a deposit. Asked them what their best price was. Salesman writes up an offer sheet. MSRP. I laugh and asked if he was kidding. Nope, selling like hot cakes. I said fine, off to the U.S.A. I go then. Must of hit a nerve. Tells me to wait while he checks with the manager. New offer, $2.5k off MSRP. I counter offer with $8k off of MSRP. Salesman leaves and come back with an angry manager. Manager proceeds to berate me in front of salesman

I told him, $8k off of CDN MSRP is still $4k more than US MSRP which shows I'm not unreasonable, want to keep my business in Canada but don't want to get hosed. He told me to get the #$%@ out of his dealership.
That evening I get an email rant from the manager about becoming the 51st state, how unpatriotic I was, and how it should be US prices that go up, not CDN prices that go down. I fire off an email back, copying the dealership owner, letting them know that such behaviour is very unprofessional and they would never see me again.
Now, thoroughly pissed off, I look for Sienna's in the US. Unfortunately, Toyota USA is protecting their CDN brothers, won't sell to Canadians. Low and behold, Honda will (at the time they still did

). I find a fully loaded Honda Odyssey Touring for less than my offer on a Toyota Sienna LE. Not only do I get the options I want, I also get DVD and NAV for less!
Felt really good to go back to Tony Graham and showing the dealer my new wheels. Thought the manager was going to pop a vein when 6 clients left the dealership to ask me how easy it was to import from US.

JB