If you met enough Greeks, you should be able to state something about what they have in common without meeting all of them. A similar diet in a region is one such thing, for example.
It's not bigoted. It has the appearance of bigotry, but a true bigot would refuse to lessen the severity of his opinion if he met a case that defied his expectations. In my experience gender is also a much more cohesive thing than culture, and people of the same gender do share more similar properties.
Have you ever worked at a place where you expected different quality of work from different departments?
dept. A people do invoices quicker.
dept. B people always answer the phone.
dept. C people are lazy, hedonistic slobs.
Something like that is often a benign rationalization, but has serious ramifications for how your department operates. Who you trust on a daily basis is based on a number of illogical common-sense assumptions. Holding similar opinions about women is no less benign, and often an effective heuristic in communication. Remember, I'm not advocating any sort of physical violence against them and I couldn't care less about controlling them.
What about the other possibility - why would any rational person assume out of thin air that the average women wasn't operating on pure self-interest vs. the average male? What is the empirical basis for that claim? Could it be that this assumption is what prevents most men from understanding women?
There is nothing wrong with a little bit of unwarranted over-generalization, if you know how to use it. It adds a healthy amount of suspicion in social interaction. It's like liquidity on the stock market.
