Why is my brake dust sticking?

[ChevyCantstop]

Here's some pics the driver's side wheel is the worst. Even if you clean it thoroughly (which takes about 1 and 1/2 hours) it comes back and sticks again. It's only the drivers side wheel that does this and out of 6 years of ownership of this car this is just starting to happen! I want to make sure it's not my rotors because we are replacing these wheels with some 20'inch LTZ wheels. In about 3 months!

 

[ChevyCantstop]

 

[Inventive1]

If this is only happening on one wheel, I wonder if the brake pads on that wheel are different than the pads on the other wheels. Someone may have only changed the pads on one wheel. (That is NOT the correct way to do a brake job, but.....I've seen it happen!)