Bathroom ceiling -- The new (one-coat premium)latex paint quickly wets the original paint and causes it to slough off. Because the original paint was flat and well-cured I didn't worry that it was probably an oil (because its an old paint job and that this is a bathroom). If the new latex dried and peeled I would blame myself for taking a time-consuming shortcut. But sloughing off during the application has me baffled. I scrapped, mudded and sanded a section that appeared to be down to the drywall. I then repainted the section but painted out onto more of the old surface causing a new trouble spot. After I stopped cursing, I knifed around the trouble spot but the new paint peeled back like tight, thick shrink wrap cut with a knife. I figured that I need to let the new paint throughly dry before I can tell if I will be able to limit the re-do. I don't know why the new paint did not adhear better to the raw mud job. This little project has turned into large pain. Help, please! Could the old paint be a porous latex that has allowed water to weaken the adhesion with a poorly prepared drywall? The is no mildew apparent on the old ceiling, but I did notice discoloration spots on the scraped section (i.e. on the drywall). Could there be an old weak latex paint job on top of an original oil? That might explain why the paint sloughs and the new paints peels back. Thank you.