You can keep that brake dust buildup from minimal to nothing by just Liberally spraying Eagle 1 A-2-Z tire and brake cleaner down into the center of the caliper everytime you wash the bike. Mine look like new, no dust or buildup of any amount. I also do the cars and truck, buy the Stuff in a Half Gallon pump spray bottle at Pep Boys when on sale or Amazon always has it. I use it on everything from the Ceramic tile in shower to the vehicles. It is also safe for painted surfaces such as powder coated wheels or edge of fender while spraying and the brown dirt that rolls off the tires, even when they look clean, it pretty amazing.
Only other thing I notice is I remove bags/seat/cover breather & radio and thoroughly wash the bike weekly. But brake dust does accumulate pretty fast and is actually metallic particles that rust and corrode.