Recently, I bought a PHA-1 from a Chinese online audio store advertising on TMall. The price was approximately the same as the MSRP in Japan (i.e. not the usual crazy "import markup", but not stupidly cheap either). The DAC came in the correct box, marked "Chinese market only", and all the expected accessories were supplied, including Walkman LOD and spare iPod straps. On the underside of the unit there is a serial number and a product information label in Mandarin. It sounds the same as the one which I tested at Jaben.
After about six months of light use, the print on the side panel, around the gain selector, has worn away. All other print is robust. Is this to be expected, or should I suspect my PHA-1 of being a fake?
I don't think that there are fake sony PHA-1s around. So you can be safe on that side, if you are really suspicious you can always open the unit and check if the pcb looks like the ones you see online.
But to be honest I doubt very much this is the case, this is not the kind of item that are easily copied, too many specific extras and odd shaped corners on manufacturing.
Paint on aluminum can be a function of many factors, if the humidity or temperature where not correct when your batch was done it can result in not that good adhesion.