When I comment on an image I'll rate it - never gave it any thought until reading this thread... Like Firesnuffer I mostly comment and rate images that I have a reaction to - positive or negative. And because it's an image I WOULD comment on, it typically gets a 4 or 5.

Yeah, I guess the ratings are superflous, huh?

And yeah, I've seen tons of "HOLY ---- THIS IS THE SINGLE GREATEST IMAGE I'VE EVER SEEN IN MY ENTIRE LIFE - FIVE STARS!!!!!!!!" kinda comments when I thought the image (3D or 2D) was (shrugs) "okay..." So the comments aren't always helpful or constructive.