Bulldust has achieved legendary notoriety due to use of the word as Aussie slang for 'having no substance', and that pretty-well describes the stuff out there on the bush tracks and back-roads of northern Australia.  Derived from the impact-disintegration of a silt soil-profile by constant vehicular traffic during the dry season, the stuff is so fine as to flow like water, and works it's way into every nook and cranny of a vehicle's interior no matter how good the door-seals.  Air-cleaner elements and electronic components quickly become clogged, and the driver's lungs are subjected to a good work-out as well!  Worst of all, there's usually a large rock or bone-jarring hole hidden under there somewhere to put the vehicle itself at risk!