The general and most important point I believe Freddy Krueger's costume puts across is how present he can be. Freddy murders people by infiltrating their dreams, so if Freddy can visually ingrain more of the senses into the audience's memory, the more realistic and terrifying their recollections of him are, and the more realistic and terrifying he could be in a nightmare. As I have stated above, his rotten teeth could make the audience visualize, feel and even taste his hot breath, and smell bad breath, the rotten skin could also be smelt and even touched. The thought of his leather glove could also give an impression of the feel and texture if Freddy was to touch or stab someone.