Ill respond to a no callsign read back with a blunt "who said that" transmission.
and "i can't tell who said that without a callsign, ABC123 was that you?," and the response won't correct themselves, it will be "Affirm"
But the most tiresome I think is the "confirm" at the end of read backs. Some airlines are woeful at this. The read back is usually perfect followed by "Confirm" and if you don't confirm it for them, they ask again and again and again followed by my response, "..if I don't correct you, that is confirmation that you have read back the clearance correctly, please don't waste my time by having me repeat myself."