...how do you know I don't have a female partner?
...or perhaps I live with my sisters and we're all the ladies of the house?
...or how can you tell I'm a Lady, and not, say, a Countess?
...and even if I am this household's head female, why would you want me in particular as opposed to any other theoretical human in this household who might be entitled to spend money, since all you're doing is selling stuff door-to-door?
...or are you just trying to sound polite, and instead making me wonder what century you've come to me from? And where are all my servants, now that you've implied them?