I've flown with some pretty experienced pilots (including IR holders) who are terrible on the radio, but who is going to correct them? ATC don't do it (not suggesting they should)
We used to have an annual air show at EGCB years ago, and two professional (and very switched-on) ATCOs from nearby EGCC ran the tower for the weekend in place of the then A/G.
I remember one exchange to this day:
ATC: "G-AB are you ready for take off?"
G-AB: "Roger"
ATC: "G-AB is your 'Roger' an 'Affirmative' ?" (it was while ago)
G-AB: "Errr. Afurmutive"
....So it can be done
SSD