I have to agree with Annamel on this one. Do this to see how incorrect you are: go to your local Wal-Mart and walk to the middle of the store. Now look around for an exit door. You can't see the actual door because of shelving, can you? Now, picture the entire store filled with smoke so you can't even see the door from 15' away. These signs were mandated because people DIED trying to find a way out, but they couldn't see the doors.