To be honest I haven't washed it since I applied the wheel armor as I've only driven it once.
Apparently once you apply it you can just high pressure hose off the brake dust or wipe it off much easier, but what it is supposed to do is make it much harder for the brakedust to adhere to the wheel. If you are able to clean the wheels very often then you shouldn't need it, but it will mean less scrubbing and risk of damaging the wheels.
1speedbike, what it possibly could be, is that rather having the other 3 wheels painted, it might be that the dodgy wheel is the painted one. You will find that painted wheels generally chip much more, though that might be more to do with the quality of the paint job and paint used etc. It was definitely something that I noticed when my wheel was repaired. I never noticed any chips at all on my OEM wheels. Maybe it was a bodgy job and that's why the brake dust is smearing as well as why it's chipping so much.
I think what you may need to do is just get that particular wheel resprayed. I'm not sure what it costs in the US but over here it cost me AUD$100 per wheel. I'm sure you can probably find places that are cheaper and places that are much more expensive but as the old saying goes, you get what you pay for.