SHORT VERSION: They will take advantage of you, make up BS to avoid responsibility, and do a half-assed job. $15 oil change/tire rotation became $35.
My car needed an oil change and tire rotation, so (as the car is in my mother's name) my mom called and made an appointment specifying I was coming in for the $9.99 oil change deal with tire rotation being an extra $5 as the car is an SUV. She also mentioned that she didn't want synthetic oil in the car due to its age and asked for the basic oil. The man on the phone agreed. I didn't know how specific she had been at the time I went in.
Going into the shop I told him I was there for my appointment for the oil change deal. He signed me in, breezed through paperwork and only asked for my signature without saying anything about costs and I figured that was fine as it had been pre-established (I won't make this mistake again because people are clearly willing to take advantage of a young, inexperienced looking lady).
When the car was returned to me I provided the coupon and he claimed he couldn't accept it as they had already used "bottled oil" on the car and it was more expensive. I was bothered, but figured I should have been more explicit in the beginning and maybe my mother hadn't been specific in her call as she said. However, when she called them later to complain as she had been VERY clear, he claimed when he answered the phone he probably had oil on his hands and didn't write down her instructions (first: that makes him at fault for not following customer instructions that were very clearly given, second: I don't see how he could answer the phone with oil "all over his hands" and yet wasn't able to write down her instructions...). I also got the tire rotation "done", but after every other rotation I've had done the car has accelerated/ride smoother and it is running just the same as it did before I took it in so either they did a terrible job or or didn't do it at all.
Finally, he continually told me the brakes needed replacement and was somewhat pushy about it. He offered to "take a bit off" the brake replacement prices to make up for the bad experience (the prices seemed relatively high to other places and would remain higher with a discount), not that it matters as I won't be taking my business back!