The 50% divorce rate proves they can hide them as long as they need to.
Women are very fluid and adaptable. They mold themselves to fit the situations and people around them. Once a woman sets her eyes on a man she "must have"... she will usually try to "get into his head" to figure out that type of woman he wants. Then she will play the role of that woman and hide her red flags through deception, mind games and omission.
As long as this man continues to be the "best man available" she will continue to act like his ideal woman. Once her priorities change, a BBD comes along OR she has extracted all she needs from the man (kids, money, etc.) then she reveals her true identity. And its usually not pretty.
Why do you think women like labels to much? (friend, boyfriend, husband, etc). These labels she gives to people are her reminders how how to act around them and what information to reveal to them. She can hell her beta b!tch white knight friend she has slept with the entire graduating class of 2010.. but she would never tell her beta provider husband or boyfriend the same.
This is why many believe there is no such thing as a "quality woman". Women become what they need to be to attract the man they want. But it has nothing to do with morals or inner "goodness" (aka quality).