What's up BigC. If your getting bids from people in other countries then you have something set wrong on your ebay selling (listing) page set up. I sell U.S. only, no international. International bidders should not be able to place a bid on any of your items if you do not offer international shipping. I've had plenty of messages from foreign ebayers asking to bid, but that's it.
Make sure you uncheck this box when listing-
Sell globally, ship domestically
Also, there are many of these companies that buy for foreigners on ebay, be it Japan, Korea, China, etc.. They are in bed with ebay, literally. They have multiple user id's and buy large amounts of stuff. For the most part they are legit. For the volume they are buying, if they weren't, there would be thousands upon thousands of complaint threads like the ones you linked to earlier in this post. Here is one such company that I have dealt with several times-
eBay View About Me for flight2kix
PS- for what it's worth. 1 bad feedback isn't the end of the world. Most people realize that you can't please all of the people all of the time. Granted it sucks and you won't have that 100% anymore but it's not something to lose sleep over. I remember when I got my first one, it was from a seller. I recently got another one this year and one the year before that along with a few neutrals. I still get my discount every month for being a top rated seller.