If there is a popcorn ceiling, I tell the client it most likely contains asbestos, and give them a link to the EPA website, and tell them where to get it tested. I leave the decision on what to do about it up to them, but try to help them figure out where to go next.
Earlier this week I inspected a house with several popcorn ceilings, in one room the texture was flaking off a bit, so the buyers took some small pieces and had it tested. It did contain asbestos, and they negotiated with the seller. I'm not sure if they decided to remove it or cover it, I'll ask.