Question about Alloys

Okay so I am obviously clueless about this. I've had my car for around two weeks and am trying to figure out how to get the alloys clean. Normal washing gets a bit off. Then I have a look after its dried and there still seems to be stuff there.
So I discover there is a cleaner specifically for wheels. Who knew.
Now I'm trying to figure out if the alloys are powder coated or sprayed as that makes a difference to what you can use. I've got the two tone roulette wheels if that makes a difference. There seems to be something sort of brown stuck to the silver bits.

Any suggestions? Does anyone know if these are powder coated?

Thanks

team Electric Blue