I'd feel a tad unsettled if I saw a pilot wearing a black tie
I wear sensible boots (jodphur boots), gloves, jeans and a high-necked top (i.e. polo/turtle neck) so that the harness doesn't rub the back of my neck. My passengers are either family or friends and they know how I dress so I don't see the point in pretending to be someting I'm not.
However, one always wears ones make-up, has ones nails done and looks totally gorgeous and glam!!
Cheers
Whirls