The good ones are normally snapped up at a pretty young age. Once they hit their late 20s they are either divorced (possibly with kids), have kids but never married, lots of baggage from past relationships, desperate because they are afraid their biological clock is running down and they don't yet have a mate.

You will find workaholics and those finishing up their masters/PhDs at that age who are still decent, but they tend to be women who are smart and dominant and they won't look at some pansy so don't bother with them unless you have something to bring to the table.