I think this problem with eating paint has to do with age. My golden retreiver puppy did the same thing in two different rooms of my house. She literally scraped the paint off the wall with her teeth. I can't imagine what made her choose the spots she did. She is a little over a year old now and has stopped this practice.
By the way, sheetrock mud is wonderful for filling in those grooves she created. Just apply a thin coat. One of my friends who helped me repair corners of cabinets in the kitchen that were also chewed said that the dogs won't like the taste of the "mud" anyway, so if they try again, they'll probably decide to do something else instead. If I could only keep my shoes from being eaten!