What's the true scoop on rioting planets?

[Spoo]

I think an PBW empire I took over has it, and there is no way to check.

Choose "save empire". Setup a new game and choose "add existing" in the empire screen, and then choose "edit".

[Wardad]

DOH!

That worked, and the happiness type is neutral.

I might survive long enought to make it interesting for others.

[Pablo]

I once took over an empire and in ~5 turns I had ~50 planets rioting. I took some measures but anyway after about 15-20 turns there still were some of them rioting. And none of them rebelled.