Well, any dust is "bad" - but at least there hasn't been asbestos in brakes for a long time now...
Guess us "old farts" assume too much, like you don't blow it at yourself and if you get a bigger cloud than expected you just stop breathing for a sec and move away 'till it settles.... used to be considered "common sense"....
And while on the soapbox, "caliper cleaner" is a new product that has no functional use - rotors and pads need to be clean, calipers only need clean contact points (usually a matter of filing rust away....)
As whynot mentioned, chemicals can attack rubber components, so any used on assembled calipers should be kept away from the rubber parts - as in wipe with a dampened rag, don't "wash" with a spray can....
Making things pretty can be fun, many enjoy it more than "functional" work - however, you can easily cause yourself problems when not done "just right". Think of brake painting as if you were painting internal engine components (wow, look at that cool cam....) getting paint on functional areas is a BAD thing, paint flaking and getting where it doesn't belong doesn't help either! Chemicals or paint damaging rubber seals leads to damage and early repair/replacement - so be careful!
I once painted a set of complex ATE brand calipers when disassembled for rebuild with a proper ceramic paint caliper paint kit. masking/greasing areas not to be painted, cleaning them after painting, reassembling without paint damage along with careful installation on the car - looked good when done but too much work for the result. And when they needed to be replaced anyways a year later due to overall age & wear it really felt like a wasted project....