I bought a 2015 Mazda3 from Mazda Stoney Creek. I found the experience to be an easy-going low pressure adventure. They had lots of cars to choose from. I ended up with a 'certified' used car, which means that they do additional checks, allow you to return within 7 days/1000km and extend the powertrain warranty.
I felt very confident with my purchase walking out the door. Then 'oh no!' I found rust on part of the trunk lid - a small hidden patch. I still wanted to get it fixed and got an estimate of $200 from a body shop. I then though I'd ask Stoney Creek Mazda if they would cover it being so soon and being certified. Didn't really think they would, but to my surprise they were quite willing to fix this small but important problem.
After a bit of back and forth, I got to my appt, left the car to see what I get back. To my pleasure a completely professional fix was completed and you'd never know there was rust in that spot.
So overall, I'm pretty happy with the entire experience.