I can't say about Amazon in particular, but I have some cheap Chinese 3" shield cut feathers that I may have ordered on Amazon (not quite sure).
So far they have been fine. They seem to be similar to the Gateway feathers that I have. In fact I have a set of arrows that I used both Gateway, and the Chinese feathers without any problems. The shape is very slightly different, but the surface area is about the same. The arrows fly better than I can shoot.
When I'm in the zone I can put 3 arrows into a 2" group from 20yds.
If only that happened more often.
So far I haven't had a feather that I had to toss, but I have heard that it can be an issue with these cheap feathers. At the price I paid I won't mind if 10% end up being tossers.