Sometimes after 8 hours on a busy day trying to get read backs from students who are 'learning' RT and lazy/inexperienced/poor instructors who don't jump in and finish/correct the read back and leave ATC to chase it, when they have more important things to do than the instructors job.
It's the instructors job to train the student, don't be so lazy as to leave it to someone else to do. I'm sure the 'not good enough' comment was more aimed at you Ratso as you sat there FDandH making the Controller do your job. If you find it too hard to do your job for the entire flight including taxi... get out of the right hand seat.
To everyone else besides Ratso, lets be honest, as Fixa24 said, we all have bad days and say things we regret. Pilots are as guilty of this as Controllers. Build a bridge.