From the information linked here so far:

a) Normal operation does result in read errors directly off the disc of maybe up to 1-200 per second. The CIRC process corrects ALL off these so the net result out of the transport is ZERO errors total.

b) This result is to be expected in all but pathological cases: brillo-padding the CD and dropping the transport from a great height would be considered pathological cases (but since that latter problem is intermittent, "anti-jog" mechanisms in "discmen" solve even this by specifically allowing rereads)

c) any transport not achieving such performance (whether that be through laser biasing or whatever) is given a special designation...BROKEN!