Strange rumors about Belize being anti-American...
Based on sailing thru Belize, listening to a year''s worth of discussion on the Western Caribbean Maritime Mobile Net (based out of the Bay Is. but including many crews, mostly American, thru-out Belize for extended periods), and talking to a number of folks who have cruised and chartered there, I think the info you''re getting is offbase and relates to touring generally but is not fairly categorized as ''unAmerican''.
Belize is poor relative to the U.S. but middle of the road relative to the Caribbean; for ''poor'' you might consider Jamaica, the DR, Honduras and of course Haiti. Americans in particular can be atrocious guests in a foreign country...but so can anyone else. I wouldn''t consider the info you were offered to be relevant to your chartering plans; just be a good guest.