The main reason is because these Chinese pirates manage to produce and ship their products much faster than other manufacturers. By the time that the real product arrives in China, consumers believe the real product is a fake of the "original" Chinese version:
LG was so slow in getting its Chocolate phone released in China that the pirates put some excellent copies into the shops. When LG did release the phone, it failed because the discerning Chinese punters thought they were fakes copying the 'original' Chinese version.
Chinese pirates cloned the PSP fairly successfully and even chucked in a stack of pirated Nintendo games to go with it.