On the other hand, we have seen some of the best entries fall down because they didn't work. We tend to look down on a prime number printer, that claims that 16 is a prime number. If you do have a bug, you are better off documenting it. Of course, a correctly working entry is best. Consider using misleading or subtle tricks layered on top of or under an appropriate level of obfuscation.
Small programs are best when they are short, obscure and concise.
While such programs are not as complex as other winners, they do serve a useful purpose. They are often the only program that people attempt to completely understand. For this reason, we look for programs that are compact, and are instructional. One line programs should be short one line programs, say around 80 bytes long. Getting close to 160 bytes is a bit too long in our opinion.