Are OEM wheels painted in the factory or powder coated?

I don't think you can say powder coating causes failures full stop.look at companies like VMR who offer custom powder cost finishes when you buy their wheels, DPE de same. I had my CSL wheels reurbed by Lepsons as do many of the CSL guys and they our a someone weekday are bullet proof, I think it is more down to poor quality casting or was someone else said the wheels not being cooled properly

I don't think anyone's saying it's as black and white as that. But if you read the information in the links I provided, for example, it explains that the wheels are cast in a way that allows for the extra 'ageing' that the stress powder coating process adds when new. Subsequent powder coatings are not taken into account at that stage so depending on the wheel design and margins for this sort of thing, the heat from the process applied again could be enough to make imminent failure likely.