On my User CP:

The rep with the blue balls hasn't changed the total rep like the green ones did. What are the blue balled reps?
KingKong
2011-02-05 18:51:09
Neutral ones? They're like in between red and green.
But if you go a rep a post, you can only give good or bad…Confuzzled :confused:
It means that user has 0 rep power.
Edit: When their power goes up to at least 1, it will turn to green. I don't believe you can de-rep until you have > 0 or maybe even > 1 rep power.
Markus
2011-02-05 19:04:12
IIRC, that happens when you don't give rep out yourself. The reputation you receive maxes out at a certain point.
KingKong
2011-02-05 19:09:25
I think its supposed to stop people from making multiple accounts and giving reps to themselves from an acc that has no rep itself.
YoHoJo
2011-02-05 19:20:21
It means the person who gave you rep has so very little rep themselves that they have 0 rep power, giving you no rep.
Brain
2011-02-05 19:21:51
someone got them really excited then immediately left them high dry. Probably causing some kind of discomfort…poor guys.