I gave someone a negative rating on here.  I fully explained what happened and what I did to try and correct it and what they did in response to what I did.  Nothing happened.

Though it did not happen to me, you also run the risk of them reading things here and in turn giving you a negative rating. 

But remember, you can respond to a rating someone gives you, just like they can post a response to a rating you would give them.

I thought my case was worth the risks.