Usually there is a warning. Sometimes it's just part of the newsletter. Other times, they send out a dedicated mail. What I'm saying is that you are probably best off just monitoring the product page from time to time, and don't just rely on Sideshow sending out a warning. But I guess that's up to you.
There were some eyebrow issues, correct. It's pretty much varies from piece to piece. The problem was that the paint wasn't really applied correctly to the sculpt. Some collectors managed to fix this themselves with not too much of a hassle. Others chose to simple have the entire thing repainted.
I believe there were also rather noticeable differences in the green colors from piece to piece. Some had dark green faces, others a more yellowy color in the face area. It seemed quite random, to be honest.
