The member rating is simply a peer assassination tool. You can give any member a rating and vice versa.As recceguy pointed out, it doesn't guarantee anything in particular, and may show how only one other user felt.
Still, it's another piece of information you can use (or not) when judging a given response.
If you want more info on a particular rating, just click on it. It'll tell you how many votes there are, which can give you a better feel for if it's just one guy's opinion or more of a general consensus.
Hope that helps.
Cheers
Edit: I should also point out that you can opt out of being rated by editing your profile. (Edit Profile --> View/Update Profile --> Allow your user rating to be publicly displayed?)
[ 22 July 2001: Message edited by: Mike Bobbitt ]