I've seen-- and a couple of times been the "victim" of-- instances
where an actor who is talented (and may have been brilliant
in a recent mainstage production) but can not read English has
been cast in a reading and when the problem shows up in rehearsal
nobody has the guts to discard him or her and get someone less
talented who can read. I know this sounds weird: but over the
years I've seen it with dyslexia, ESL, and blindness!! Sometimes
the actor compensates in rehearsals by near-memorization, but
performance nerves bring on brain cramp and the actor just makes
up lines.
by 
