I am not sure what you mean there because users have to be able to comment to be able to rate a photo. They are all done by the same permissons structure in the software. The only permissions structures different is voting which is for the contest feature.
The one feature set in the admin options that shows whether a rating is shown as an empty comment with the rating is the one you meantion and you set that as you wish.
If you set it to display empty comments then it will display those empty comments with just the rating
I would highly suspect an issue with some sort of modification because if I just place a rating on a photo and have that switch set accordingly they show. here is an example naughty boy - PhotoPost Photo Gallery