> So someone selling (let's say) hamburgers might be savvy enough to avoid vegetarians, but after that how would they possibly narrow it down? Not everyone wants to try out a new burger place, or even cares about advertising when it comes to restaurant suggestions.

One of the examples in the posts describes ads for products that aren't even sold in his country. I feel like limiting your ads to people that are or live in a country you sell your burgers in would be a good start.