I know what your saying, on some of the other forums I use they have a more structured sales approach in the for sale areas. Putting rules like that in place just gives the mods more work to police it, and might put some people off from wanting to advertise sales stuff if they need to adhere to xx or yy rules.
I'm sort of with Val on the if it ain't broke don't fix it method.
Odds are anyone who wants to implement rules like that will already post sales add with a picture, location, and price etc.