Solarized Dark's colors by themselves are fine. But when you compare it to the renders and what people were expecting to receive... oh boy. There's a reason there was so much backlash against the set when it released. GMK Necro is another set that was very off from its renders.
Sure colormatching can fail if you do it wrong or use the wrong methods and did so in the past for some sets.
Sol Dark was probably my favorite fails since it looked nothing like the renders but still ended up being a really nice looking set.
Necro and Plum are a different story though...
But with the technology that Omnitype (and many other groupbuy runners) now use for their colormatching it is very unlikely to get a set that has the colors that far off.
Nebulant (the guy who does all the colormatching) uses a spectrophotometer to match the samples. You can't really get more accurate results than that.