Though I have never gotten bad feedback, I was just wondering if there was anything you could do if you believed you received an unfair rating on your feedback?
If you present concrete evidence to a moderator in a PM they can remove the feedback, but sometimes they don’t. In my case the guy who traded with me incriminated himself publicly and they removed it for me. In someone else’s case I thought the guy was clearly leaving revenge feedback after his own mistakes but they didn’t remove it.
If it’s iffy I doubt they will change anything.
Cool cool 
I don’t know why, I’ve just always wondered that for some reason…
This is one reason it’s important to keep your pm’s with the individual you are trading with. It allows the moderator to get a clearer picture of what the agreement was and how the situation unfolded.
Clear communication and follow through on both parties part are a must.