The horse meat scandal is a good example of that. Turns out that there are all sorts of people who have been eating horses that have no idea that they were. Millions of people. The basic reason that they were is that horsemeat is very cheap, compared to beef, and if you can sell horsemeat at beef prices you'll make a good profit.
When you go back to how the horsemeat got into the food chain in the first place what you find is that there are a large number of transactions between the farm and the plate; sometimes as many as 15 different transactions, and across many different countries.
Now mind you that this is not the first time that this sort of thing has happened; there was a fast food resturaunt chain that was selling kangaroo meat as veal, for instance.
So I was reading a farming industry newsletter, and was surprised to find that mainland china had banned US pork from being sold there, along with the EU, Russia and Taiwan.
Now why would all of those countries, where people enjoy eating pork, ban US pork?
In a word, Ractopamine
The basic idea behind this particular feed additive is that it promotes lean muscle mass. Opinions vary, but the general consensus is that meat produced using this additive (known as paylean for swine and optaflexx or Zilmax for cattle) isn't as tasty as meat that does not contain it, but for feed lots and producers, it means pounds of meat per pound of feed, and that's attractive to them.
I don't know about you, but when China bans a feed additive...
Ractopamine is used in most meat found in supermarkets these days. it's used it most pork found in the meat case. This is a case where it's worth knowing who your farmer is.
There have been concerns by the meat packing industry that the animals produced aren't as tasty, and some would reject cattle fed ractopamine, but those restrictions didn't last very long. I guess this is the animal equivalent of those rock-hard strawberries that you could launch from a cannon. They look great, but who cares what they taste like?
My animals don't get any feed additives of any sort. They're naturally delicious.