Have Trudy ask this other "friend" if her dog has "accidents" at other peoples houses. If she says no never then Trudy knows she is either lying, in denial, or just doesn't care about other peoples property. Either way she then needs to tell her that her dog left her some surprises all over last time. She can then give her a choice. 1) Leave her dog at home or 2) find and suggest a small room, without carpet, put the dog in, close the door, and she clean any surprises left 3) she also can keep the dog on a short leash. If this "friend" never talks to her again tell Trudy she'll still have you as a friend.