We're also left with the impression that that Lynn has a strong unconscious need to hate brunettes and love blondes. It seems to me that the reason why Connie stopped being an antagonistic jerk and why Lynn abandoned her plan to make Susan a threat to Elly's marriage is that she simply cannot bring herself to hate women with fair hair. The reason seems to me that she associates lighter-colored hair with a redeeming passivity that doesn't threaten
As for dark-haired women, the only good one is Georgia because she freed Phil from his nomadic lifestyle and playing discordant noise that
While it might seem that she's profiling people because a brunette got more action than she did or because Alan is a brunette and won their childhood by 'cheating', the explanation might be even more simple. All we have to do is find out what color her mother's hair was.