This reminds me of something I saw a while ago on the tube. Sitting opposite me, and next to each other, were a blind man and a young guy of about 20. The young bloke was trying to engage the blind guy in conversation, genuinely trying to be friendly and helpful, asking if he wanted to be told when we'd reached his stop, that sort of thing. The blind guy could obviously manage perfectly well by himself and I got the impression he was maybe getting a bit annoyed by the other bloke's attention.
Then the the blind guy got up and left the train and who should sit down in his place but an albino. Fortunately the talkative young fellow managed to hold his tongue. I had this little fantasy about a dwarf with three arms or something getting on at the next stop, and the poor lad sitting there getting more and more freaked out...