Trying to patch
plaster is a waste of time because it will never look like new. If it's a
fancy molded ceiling in the livingroom it might be worth a try, but
certainly not worth the hassle for a bathroom.

Whether it looks like new is immaterial-- for the time being anyway.
Getting drywall can be a lot more trouble than it's worth; is that DAP
plaster stuff, or any similar products any good?

Ron