Good points, David. All realtors list property in Belize in US dollars. But, as you note, pretty much any associated services provided in Belize are priced in BZ dollars. And when you get to Belize you find that some restaurants show prices in US dollars. If they do, that should be noted on the menu.
At International Living, we consistently use US dollars when showing prices, as we need to price things in one currency across all countries and the majority of our readers are American. Any price we show is in US dollars unless a different currency symbol is shown. Once in a while I’ll see a price in Euros, for instance, since that is the major currency in Europe and we write many articles about European countries.