"Not interested" is a fine thing, and most of us are accustomed to seeing it at least once every contest. The important thing is you do what you need to do to stay organized, and keep the entries moving in the direction that suits you best. I'll often post two or three variations at a time, and it helps to see your preferences, even if you don't provide detailed feedback or even a specific ranking.
Good luck, and please let me know if you have any ideas or requests.
Cheers,
John