Whenever you are cast in a play, it is up to you to then read the play as soon as possible, preferably even before the audition, but immediately following the posting of the cast.
A chat board is not a good source of info which is after all, very subjective. One person's great part is another's lousy one.
It is not bad advice to be given and ought to be appreciated rather than scorned.
Homework.
In this case David and Lisa is based on a fairly acclaimed 1961 film that can probably be had through Netflix. I think it was also a novel.
The psychiatric material may also be out of date. More homework.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher