Depends on your reason for the negative comment. If you sincerely mean it to improve my profile and has nothing to do with my attitude concerning the contest.
As long as you can deliver it with sensitivity and tact, should you try, and if you feel that I might be offended...dont ignore that instinct. You may need to re-word it or examine it to make sure that you arent crossing the line.
Fortunately I am not the type of person that stays mad. I am very forgiving. Still, follow my guidelines and I probably wont have any reason to be upset at all when you give you comment.