I rate most reviews, unless they have little or no detail or useful information.

I rate most reviews I read.

I rate the majority of the reviews I read.

A lot of times I'll rate but not comment. I guess after 4 pages of "thanks", I figure they get that we're thankful and the vote will help them out moreso than yet another comment.

I try to rate the reviews I read. Some of them are so bad it just warrants me to rate it or if it's very very good I can't help but lavish some love through ratings on it.

I usually only rate the reviews I feel strongly about, not every review.

I rate most of the reviews I read.

I rate almost every review I read.
Except in cases when: I didn't thoroughly read it, I thought it wasn't particularly useful, but can't offer feedback because way too much was missing and some of the other cases mentioned.
I don't like to be mean either, but if I do leave lower feedback, I usually ask a question pertaining to the key thing that I thought was missing.
I also leave feedback about things I really liked that the person added, especially when it is something people don't normally think of or it was really helpful.