Corrected entry: As Roxy takes Tess (Daisy's reap) out of the hotel room, she trails her fingers across the door frame and very obviously makes contact. The problem is that dead people are incorporeal, as we see within two seconds as she goes straight through the crime scene tape.
Corrected entry: Near the end of the episode when Rube's daughter is about to die and he confronts her, she recognizes him. In the first episode of the series they tell us that the reaper's faces are changed so they don't look how they used to, but Rube's daughter knows it's him.
Correction: As is evident by Georgia's sister recognizing her it seems that people who were close to the reapers can recognize them despite the change in appearence.
Correction: Tess also had no problem sitting on the floor in the corner crying while touching the walls. We do know that the dead can interact with matter some times in the pilot George walked though the kitchen door and it swings a little, in The Shallow End Stan (Mr Big Balls)has no problem sitting in a booth at Das Waffel Haus, there are many others examples.