I'm 6'5" and I'd say it works in both ways. Sometimes I'm lucky and there'll be a 64cm bike up that nobody grabs, or the other side of the coin where it disappears almost instantly because of the uniqueness and rarity. Though I am thinking more of the complete bikes I'e seen than frames. Some great 64's disappear like the wind.
EDIT: Also I was only thinking road frames. Good XL+ Mountain bikes/frames are almost impossible. Being tall is a pain, hard to find shoes, bikes, good pants. But it's easy to hide things in hard to reach places.