A cut-off is a term given (in Mario games and Super Mario Flash 1 and 2) to a part of scenery which presents strange relation between two or more tiles used or a discontianuation of them, making the level to look odd.
The cut-offs are the only flaws of scenery that appear when the user doesn't analyzes the whole level if the scenery added is complete. These flaws are common when someone adds a lot of scenery.
One of the famous cut-offs made by most of people is when a part is filled with layer 2 scenery tiles, excepting the curved edges tiles of layer 1 and they leave a little but noticeable discontinuation.
People frequently removes few points if cut-offs are spotted; the most the user made cut-offs, the lower the rate will be.