Someone just referred to me as 'tall'. I am 6'0" even. I would classify a female that was 6' as 'tall', but I've never thought of any male at that height as being anything but average. Minimum cutoff for 'tall' designation in my book: 6'3" - male and 5'10" - female. I guess this is a subjective sort of thing.
There are a lot of adjectives that we use to describe people as if there were universal agreement, but the reality is some of those adjectives are more subjective and relative than others. Where, for instance, would you put the cutoff for the terms: tall, short, rich, poor, middle class, smart, dumb? I'm sure there are many other common 'classifications' with pretty subjective elements out there.