We have discovered that the rules to this game are a bit broken. On average you seem to be more likely to loose sheep over time than gain sheep. This can make what should be a short, simple game, drag on for way too long. I had a few games where every player had zero sheep at one point and it got tedious.
Our fix was to just make the black sheep not quite as bad. We skip the rule that says the person with the black sheep loses a sheep every turn.
Receiving the black sheep or any die roll that would normally cause that player to loose two sheep, such as Sheep Guevara and Freedom, only looses one sheep instead.
That's it. The black sheep is still nasty because you can't win if you have it, and it can still make you loose sheep, but it's not so bad it breaks the game!