I agree, it's a genuine possibility. I've ordered enough things off Amazon to be genuinely concerned about the state of cheap Chinese chargers being sold through there. There's no good reason to allow a vendor to sell a product that is unsafe, uses counterfeit labeling to bypass US electrical safety inspections and regulations, and easily threatens the safety and welfare of consumers. We can hang Samsung out to dry when its batteries catch fire, but we can't do the same to Amazon for selling us this junk?
My own anecdote: Our school district ordered 10 HDMI-to-VGA adapters recently from Amazon. They were Chinese-direct w/ Engrish instructions and the like, but I knew I was going to get that. What I didn't know I was going to get were incredibly, incredibly cheap 5V 1A chargers, only one of which was spot-on 5V, three more were within +/- 5% of 5V, five were about 5.5V (which still worked, but is not as safe and out-of-spec), and one that would start at 5V for about a minute, then float up to about 20V, before floating back down to 5V. Needless to say, the video adapter paired with the one that floated up to 20V had its display glitch out every-so-often, and even after I tried using a good 5V power adapter, the video adapter was permanently glitchy at that point.
About a month prior, I bought some other video adapters that also were powered by 5V 1A power adapters, but the stickers on the power adapters said they were 9V 1A adapters, even though my multimeter said they were running at 5V. (Sticker also said they were UL listed. Probably just as truthful as the 9V spec was.) I didn't trust those adapters worth a dime, but I wanted to see what was inside them. Unlike the wall-warts of yore, most cheap adapters now (including these) can be opened with a single screw. Inside was a little PCB stuck to the inside plastic cavity with simple double-sided tape. Most shocking to me: The PCB boards were hand-soldered, as evidenced by two of them having etches scraped into the board where solder appears to have overflowed onto other joints, plus that some joints were cold, some were gigantic blobs, and it was generally very sloppy solder work. Also concerning: the wires connecting the plug to the PCB were also hand-soldered on both ends, and more-than-half the joints were cold. One of those wires was also rusted out, and broke off the plug as the device was opened. (There was no tugging on the wire; just twisting it snapped the wire off.) Finally, one of the transistors had leads about 1/2" long off the PCB, and the transistor was bent so hard that one of its leads was dangerously close to a capacitor lead, all on the high-voltage side of the PCB.
This explains why Amazon can make a profit selling 5V USB adapters for $1.50 each, or 5V power adapters for $2.50.