I mean... they're going up on eBay for hundreds or thousands of pounds. Are there really this many defective ones? Are some dodgy people literally snapping parts of Amiibos to pass them off as 'broken'?
I've only heard (like seen a news site deciding to post about it) of 2-4 actual DEFECTIVE Amiibos, and a quick browse of ebay only brought up a couple truly defective ones. Most were packaging errors. From a statistical standpoints, even if there were hundreds of truly jacked up amiibos coming through the system, there's hundreds of thousands of figures out there- It's not something to ever be concerned about.
It's a new product by Nintendo, which has the dual uses of both being usable in games AND being actual Nintendo character merchandise which is often hard to come by, especially outside of Japan and especially for less common characters like Fox McCloud. They're something special, and between that and the newness, they're just in the media a lot. Makes the situation seem bigger then it is! Besides, people are always jumping on trends on Ebay trying to get money, I wouldn't put it past anyone to alter a figure and attempt to mislead people on ebay.