This is what the cards apparently said:
1. Korea: According to the cards, I feel uncertain about teaching there, but in the future I would be very good at passing on knowledge to other people (so good teaching opportunities perhaps?).
2. Vietnam: Very good, strong positive card, representing future hope, peace and harmony. So I could have an awesome, empowering experience. But then I got the "tower" card, apparently the most negative card representing death or chaos (see picture). So Vietnam could be an amazing experience, but also really bad. Like, someone could die. Or alternatively, "you might feel emotionally like your world is crumbling around you." Hmm.
3. Poland: This one had the most straightforward positive cards; however, nothing really remarkable about it. The main reason I'm interested in Poland is that I would be so close to the rest of Europe, and Poland currently has the highest demand for English teachers in Europe. But hey, Europe is overrated. OK, maybe not overrated, but there are so many equally awesome parts of the world.
So while it was definitely need to get another kind of input on where I should apply for jobs, the tarot cards didn't help me narrow things down too much. Oh well. I think a lot of this kind of thing should be placed on chance, and adapting to whatever presents itself.