ON +/-

I was about to review the movie Pineapple Express which would receive a C+ when I realized that I had just given Brazilian Girls a B-. What's the fundamental difference between those two grades? Is it like a line on a scale? Rather than using the + or - as replacements for smaller incremental markings on a scale, I look at this this way. Pineapple Express was basically a C movie, it was okay, the jokes were pretty good, the pacing was sometimes off, and whatever, but it had the addest great value of the chemistry of the cast and that they all seemed to be having a good time. That augments how I felt about the movie, without changing what I feel the overall quality of the movie was.
Brazilian Girls' "New York City" is a good album, but there's some weird lack of artistic zeal, some hidden bit of daring that holds it back just slightly. It nags in the back of my mind and makes me question giving it a B, but in the end, it's still a good album. Not enough to take it down.
C+ is an average thing with things that push it slightly upwards. B- is a good thing with the minor niggles that keep it from being close to an A. Make sense?
Probably not.