Editors have specific guidelines they must follow. However, these are often vague (especially if it's hard to tell, for example, if a term is just explaining a racial slur, or if it is in fact racist).
If your definition doesn't get published, it could be for one of two reasons:
A) It wasn't that good or
B) Someone just didn't like it for some reason.
In that case, try again...
However, bitching about them probably won't help.
Other person: "Get a life."
2. A group of Urban Dictionary users whose goal in life is to spread new colloquialisms, lingos, and jargon to the youth of today.
3. The people who reject other people's definitions, then publish the angry slurs against the editors just to spite the poor sods.