Yes and no. I'll usually be more polite to women when I first "meet" them. But, as Frank Zappa once said, "Women, you can act like an a-hole, too. Don't act like you ain't got one on the bottom of you.", I will cease to do so if they are adamant on being a-holes.
There have been a few that I thought were male, and didn't find out otherwise until many months later.