Q.A recent customer wanted to do his own painting and used an airless sprayer to apply primer to the bare drywall. He then rolled on the finish paint, but now he's complaining that the surface is rough wherever the drywall finisher sanded. He is blaming the drywall contractor, but I'm not sure that's fair, as I haven't had the problem before with this drywall sub.A.Drywall contractor Myron Ferguson responds: Something similar happened to me in the past. I taped a house to a Level 4 finish, which should have been good enough because the rooms were relatively small. The homeowner...