Compared to its gen equivalent, nearly every replica (and not just Rolex) have its own share of flaws. It's up to the prospective buyer to accept which flaws they can live with, then choose the model/factory/version with the least flaws or the flaws that they can live with.
As for which flaws you can live with, it's up to you to do research and choose which model/factory/version you are willing to compromise and buy.
Your open ended question is hard to answer because it is subjective as our experience and acceptability of flaws are different.