Here is a proverb from my book-o-proverbs.
글씨 못쓰는 놈 붓 고른다.
geul·ssi mot·sseu·neun nom but go·reun·da
handwriting can’t-write-PRESPART guy brush fix-upon-PRES
A guy who can’t do handwriting fixes upon his brushes.
“A bad carpenter quarrels with his tools” might be an equivalent proverb in English. The meaning is that people who are bad at their jobs frequent complain about the conditions.
This makes me think of the typical English teacher working in Korea, for some strange reason. I’ve been spending more time than usual (and thus too much time) surveying the blogs and neverending pessimistic commentary of EFL teachers, lately, I suppose.