Or maybe it's better if the user has more positive than negative, then is dark green positive ratings, and orange negative:
+10 / =1 / -6
but if the user has more negative than positive, then positive is green, and neg. red colour:
+2 / =1 / -10
Looks good. I still dislike the multitude of colors but that's an acceptable use case I think.
Yes, I agree with you, there will be more colours, but I believe all campaign managers will support this idea. that would help them a lot when selecting participants.