We do listen to the read-back, and correct if wrong.
But there are times when a pilot, being one myself as well, where you hear an instruction, but are not certain if what you heard was correct, then, as a pilot, I would use "confirm".
There are also times when you can hear on a pilots voice that he's not really certain if the instruction he heard was correct, not using the exact word "confirm". In that case I put in the word "correct" before going on to the next task at hand. I'd rather have a pilot lingering around who is confident in what he is doing, than someone who is uncertain about if he's following the right instructions. Pilots are emotionel people, and they need caring
