One of the dangers of being a writer is reading and re-reading your own work so much you have no perspective at all. I often tell students that if there's a particular word or phrase that seems to stand out or ring for you, that usually means it's really bad! If you re-read often enough nothing seems to stand out. Sometimes the work feels so familiar you can't make a judgment about it at all.
That said when writing a play the number of drafts to be written and re-written can be dizzying! Which is one reason it's great to work with a dramaturge as I did for several years with old friend and director, Harry Waters Jr. on Waiting for Giovanni. An outside voice can point out things my eye can't see any more.
That invisibility is really distressing when you're trying to promote a play that's already been staged locally. I frequently go back to the script to package it up, refine the description and send out to yet one more theatre that will probably stick it on a stack that is 4 feet high and looms over an overworked/underpaid play development director.
It's then that despair can creep in: are those words still sharp, meaningful, funny? Was the audience really laughing with it or at it? Do those characters jump off the page or merely languish? Has the impact seeped out of the script down into the floorboards leaving a stack of bound boring pages? Which is worse: a play development staffer being bored by the script or puzzled?
With Waiting for Giovanni I have the benefit of going back to the video. Even though video documentation of plays is usually flat and unable to convey the energy of live performance sometimes it is close. I recently viewed one of the monologues that New Conservatory Theatre posted on YouTube (it's kind of like Googling yourself but less embarrassing) and got the treat of revisiting the stellar performances of Wm. Hunter as Jimmie and Desiree Rogers as Lorraine. It's worth a look if only to see what actors can really do!
https://www.youtube.com/watch?v=PDeD5PjAfxE&index=5&list=TLNy_CC5nh65o