I'm not paticularly familiar with the countries you cite Christopher, but I do agree that wider culture is also important. For example, I spent some time living in France, and can say that one of the biggest cultural faux pas made by foreigners is very simple - not saying "bonjour" when entering a shop, restaurant, taxi, etc. The effect that this has is immediately to put the other person's hackles up.

I have the good fortune to speak French, but even if you don't making the effort to learn at least the basics (hello, please, thank-you, goodbye, one, two, three, beer, etc) is appreciated there. I always go out of my way to pick up these basics wherever I go, and the same applies in most other countries (interestingly IME it seems least appreciated in some of those countries where there should be a low expectation that a foreigner speaks the language - Sweden, Norway, Denmark, etc, and most appreciated where the language is a common one, such as Spanish, French or German).

Equally, in poorer countries you should not assume that the person doing what would in your country be regarded as a fairly menial job holds the equivalent social status in that country. Often, the impact of tipping distorts local economies to the extent that jobs that put people in contact with tourists are more attractive than many others. Cuba is an extreme example of this (and I use it to illustrate the point, please, rather than to open a debate on Cuban social policy). In Cuba, the brightest students go into medicine, technology, teaching, etc, and must serve at least 3 (I think) years in that profession. However, as everyone is employed by the state, and everyone is paid the same wage, regardless of job, a bellboy earns more than a doctor. Guess what people want to do for a living? Would knowing that your bellboy or barman could be a qualified doctor change how you interact with them? It might do for some... that in turn might affect the level of service you receive.