I also rarely take taxis in other countries, with the exception of Bangkok, Thailand, where taxi fares are no more expensive than the Sky Rail. While Thailand is supposed to be less civilized than Hong Kong, there is no such stench in the taxis. Obviously, their taxi drivers do not steal a drag in their taxis like their Hong Kong counterparts do.
The phenomenon of smelly Hong Kong taxis (and, of course, minibuses) is a clear reflection of one important aspect of the Chinese culture - that things behind the scene can be quite different from what is displayed in the facade. Dodgy behaviours do not matter as long as they are not caught out. In any case, the mentality of doing business in this supremely pragmatic part of the world is that you get the particular type of service you pay for. No more. No less. In the case of taxis (and minibuses), the service procured is taking the passengers to the destination in the shortest time possible. All else is quite irrelevant. This is the unwritten agreement between the service provider and the customer. The latter does not mind that the taxi stinks as badly as the attitude of the driver, who is happily blaring into one of his seven mobile phones in front of the dashboard. When there are no expectations from the passenger, why should the driver bother?