I loved calculus because about 4 weeks of teaching provided the foundation for everything else. My tests usually involved me having to derive something that was apparently derived in the book and then 'applied' on practice questions that got the 'right' way of doing things in by rote. I lost points for that.

I would also lose points for "not showing my work", but if you can't factor, say, x^2-9 in your head, maybe you have deeper issues.