well, I guess it depends on how you use it, is it a noun or a verb.

If a verb unslop means to reverse. I thought that was a more interesting idea.

As a noun I think you would not use unslop to mean the opposite of slop but rather non-slop.

Based on my grammatical preconceptions of how I would use slop I felt that unslop had to be a verb, and the contest should somehow reflect that.