I've said it before but we've got a Chinese 150cc quad and it can't be killed no matter how badly it's abused. The rims were a little soft and bent easily and the ignition shit itself once. It was replaced for $30 and the rims can be had for a similar price complete with tyres! Sure they're crap but they're cheap and really aren't as bad as the "I know a bloke who's got one" doomsday merchants will tell you.
I've been around long enough to remember when Japanese bikes (and cars) were shoddy pieces of shit. Look at 'em now. A good example is in Suzuki who couldn't produce a motocross bike worth diddly shit until they stole Eric Cheneys frame design and hired Swedish rider/engineer Olle Petterson to develop the motocross racebikes. One year later they were winning GPs. I've read that a number of Chinese manufaturers have been hiring American, Swedish and Japanese engineers and consultants so you can bet that it's now only a matter of time.
Remember also how we all laughed at those tinny little Korean cars? Have a look at the good honest products Hyundai make now and check out their market share. Once the Chinese get their small details together they'll follow suit.