+1
In university I found the worst instructors were the brilliant professors. They would constantly ramble through theory at lightening speed and then get frustrated often saying things like, "come on people this is dirt simple we can't spend all day going over this stuff." Basically they were just to "smart, good, talented, whatever" and they couldn't understand why the rest of us couldn't pick things up quicker. It was frustrating for the prof and for us students.
I found the same when I got my pilots licence. My first instructor was a class 3 and did an excellent job of teaching me. He didn't have loads of airline or bush time but he understood why I was having a hard time with some concepts and thus he was able to find the right technique to get me past my trouble spots.
Later on I've had 1 or 2 checkouts with "very good / experienced" pilots and the checks were horrendous. One guy did a demo circuit in a 185 at 300 feet and cut the x-wind at the edge of the departure and the base at the end of the approach. I guess he wanted to show off his awesome skills but needless to say it was a very painful experience trying to learn from someone who thinks it's all child’s play and has very little paitience for new pilots who are just learning.