I also made the same observation as hullexile. There's a Western guy riding the same minibus as I. And in 80% of all cases the last free is the seat beside him.
He didn't look like he was sweating a lot and rather more like meeting hygienic standards. Maybe most of my Asian fellow-passengers are just not used sitting to a person who's more than 1,80m tall. I mean (sorry pun here) he does stand out from the crowd.
Still I would not consider that as discrimination though... only some sort of reservation.
