I have had good experiences with dealers, but in a city like Toronto there is plenty of room for shady examples. We have at most two dealerships for a brand (sometimes just one) so they can't afford the word of mouth.
I brought a 1980 GMC I had just bought to one of the Chevy/GMC dealerships for an inspection. They charged me $C 80 [$US 65] and gave me a complete itemized bill of health on paper, went over it with me, indicated on the sheet what needed to be fixed now (nothing), what needed attention but could wait (a few things) and what was good to go (most things). No pressure, no bull.
Same thing with my Mazda, good dealership (the only one) that was honest and trustworthy, zero upsell, did the alignment I asked for (new wheels / tires and a used vehicle; I could tell by the old tires the alignment was necessary) and cleared the floor drains (in convertibles, they assume water will get in sooner or later because convertible, and there are drains to carry it out that sometimes get plugged with debris like blown in leaves) for no charge. Gave me an accurate assessment of my brake pads (front good, rear 10% pad life left) which I was able to confirm by my own inspection.
The Mopar dealership (there are two) did the recalls on my 1996 truck when I bought it in 2005, no charge, and a two week wait for parts. Free ride from and to the dealership and offered the courtesy car (I didn't need it, was working all day so the free rides were perfect). Again, no attempt at upsell, good experience overall.
I did go to the other Mopar dealership about a service item, but they were not so angelic ... tried to upsell me immediately and parts prices were about 20% higher than at the other guys. So I guess I can't say it never happens here, but at least there are options.
Both the Chevy/GMC and the "good" Mopar dealership offer a flat 15% off all parts if you can show you're a member of the local bona-fide Car Clubs, and the Mopar dealership sponsors the Circle Track and offers parts discounts to teams, and carry a good variety of third party race parts (Edelbrock, Kirkey seats, etc). They charge me $C 4 [$US 3.25] for a genuine Mopar oil filter for my truck.
I also have been to the Toyota dealer (only one) for a few items, like Shin Etsu grease, which you can get Toyota branded. Good price.