My gf is 6'1". She's not the 'dressy-up' type (or, as she says, "Not one for wandering around like a tart/with my t*ts on display") and doesn't do 'bling' or make-up, though it's still perfectly obvious that she's female.
The number of times people have addressed her as 'Mate' is pretty staggering. It's as if they get the impression of height and their brains short-circuit.
I've had people assume I'm gay once or twice. When I've put them right and asked why they thought it, the response has been 'Don't know', followed by a moment of thought and an addition like 'Because you're quiet' or 'Because you read' or 'Because you're a bit of a loner' (which is an understatement; calling me a 'bit of a loner' is like saying a tiger is 'a bit fierce').
Now that kind of thinking short-circuits my brain. Male + quiet and/or a reader and/or a loner = gay? What kind of logic is that?
(On the other side of the coin, when I've mentioned those assumptions to a couple of mates who are gay (and who definitely aren't quiet, or loners, and one of whom would rather die than be seen with a book), their response has been along the lines of 'You? WTF were they on?')
People are also often surprised by a certain element of my background. The response, upon hearing, is usually 'You? **** off, lying ****!'...which is, of course, precisely what people are supposed to think. Most of the guys I knew back in the day looked like anything but what they were (and in some few cases, still are).