Third world = developing...per DICTIONARY
Look, if you are going to try to get into some sort of debate about anything, the least you can do is to show you know what the basic words in your title actually mean...wouldn't that sound reasonable to you?
After all, if you don't even know the meaning of the basic terms you are using, why should anyone believe you understand whatever it is you are trying to discuss?
Which is a long way to say, use a reputable dictionary if in doubt...they are freely accessible on the web.
THIRD WORLD DOES NOT MEAN 'backward', extremely 'under-developed', extremely 'poor', 'trashy', 'banana republic' of whichever it is that you want to attribute to the phrase...IT DOES NOT MEAN THAT!
Says whom?
Many authorities...Try webster's (freely available) for example:
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Definition of THIRD WORLD
1: a group of nations especially in Africa and Asia not aligned with either the Communist or the non-Communist blocs
2 : an aggregate of minority groups within a larger predominant culture
3: the aggregate of the underdeveloped nations of the world
Want another one? Here it goes, from the business dictionary:
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Third World Definition
Collective name for most of the nations of Africa, Asia, Latin America, and the Middle East, many of which share a colonial past and are variously termed as developing, less developed, or least developed countries. ... Coined in the 1950s by the French writer Alfred Sauvy (as 'le tiers monde'), it was originally used in the Cold War era (1945-89) to distinguish non-aligned nations from the Western capitalist economies aligned with the US (the First World) and the Eastern communist economies aligned with the USSR (the Second World).
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Are you satisfied now?
So, if you are looking for a pejorative term for countries like Haiti and most sub-Sahara Africa, you need something different from Third World....perhaps you could try 'backward' or 'banana republic'...Third World won't work for that...not if you trust reputable dictionaries.