I don't know. I've never had too many problems with ISTps, but I also have never worked at jobs which required extreme attention to details, which I know it is probably not my comparative advantage. As far as friendship goes, I'm friends with a good number of ISTps, and I never had problems with them, but I don't know how do they feel about me.

As far as not knowing what I'm doing: that's true if it's a task I've never executed before, but not generally true if it's a task I have executed before. Which, well, I assume is true for most people.