The first time I took Math 165 I got an F, the second time I got an A. The difference? Style of instruction.
The first guy (I don't remember his name but it was more than 11 years ago now. The only thing I know is he smoked like a chimney and liked to have the class solve "mental problem" riddles - such as Pete was found dead on the floor. The only sign of foul play was broken glass and water was found near the body. What happened?) was only interested in teaching math theory. While I'll admit that is a good way to teach it, not all of us are geared to think that way. And if you didn't subscribe to his teaching of math theory, he really had no time for you. The second time I took it it was taught in a much more traditional sense and I got much more out of the class. It's actually the reason why my MBA-level Econ classes have been so much easier for me (lots of limits and derivatives taught in those classes).
On 166, I got a D+ as well the 1st go around (needed C- to move on) and an A 2nd time around (was ridiculously easy).
When I walked in 267 the 1st day of class and saw I had the same guy as I did for 166, I immediately tried to get in another 267 class, but couldn't do it. I even got an A on the 1st 267 test and ended with a D+...LOL.