There is a site similar to the 'I'm Bored' feature here on Cherry that enables ANY person (even non Cherry members) to rate your picture to scroll to the next one.
So, maybe the person downrating your picture isn't even ON Cherrytap and are on this site that allows anyone outside of Cherry to rate your pictures.
Makes you stop and think, hmm honesty eh? lol
Now stop moaning and groaning.
The site is called http://www.cherryphotos.com/
See for yourself.