While it's true that at my school some classes were easy to get an A in and others were incredibly hard or even impossible (and that's almost definitely true everywhere), in my school all professors used the +/- system, and as far as I remember they all used the same cutoffs for grades. So 90-93 was an A-, and 93 and above was an A. I had a few of those 92.5 A- grades, which always sting a little. And I think 87-89 was B+. No A+.
I'm not sure if this is unusual, that all the professors used the same system, but it was good because we always knew what to expect with the grading. I don't think I'd be so happy if different teachers had different systems.
Speaking of impossible courses, how many people had a course at their school that they had to take but was known to never give A's? At my school, speech communication was a required class, and since it's a small school, there are only 2 professors. One of the two teaches exactly one section of the course, and the other teaches like five. So basically everybody takes this one professor, who has been known to give like two A's in her entire career. It was an extra B in my last semester of college that I was pissed about, because for another teacher the work I did would have been worth an A. Of course if I had done less she would have given me a C!