Those last suggestions I gave were in fact based on differences that I have noticed between the average American and the average Dominican, and because Dominicans have commented to me 'hey, you don't do _______, like this other American I know did'. Maybe the average American isn't very well educated, but most do not feel obligated to tell people to come in or sit down (they assume the person will after they do so) and do not feel obliged to give anyone food they are eating, like offer chips from a bag or a cup of soda to a stranger sitting next to them on a bus. Most Americans eat food in front of others all the time without offering any, even to friends, because they assume if people want food they can/should get it for themselves.
In the U.S., I would have no problem saying to someone in front of others 'hey, don't forget about that $10 you owe me', or 'here's the $20 that I owe you from mowing the grass last week', or 'hey, how much did those shoes cost?'. I wouldn't do that here because money is a more private issue. The higiene stuff is also relevant, because it is more important here than to the average foreigner, and many Dominicans have commented to me on the poor higiene and grooming habits of foreigners. They are notorious for being dirty and smelly, given that the Dominicans often bathe twice daily and go weekly to the salon. Another example would be don't put your feet/shoes up/on the furniture, something I have seen many foreigners do in front of others, whether in their home or in a fancy hotel lobby. Generally it's not good to do, but here it IS looked down upon more because look how dirty the ground is and with what, and also people try to take better care of their furniture because it's expensive.
These are simple and somewhat more general things that some foreigners here don't always consider and it would be helpful to do so here, that's why I gave them...I see nothing wrong with that. I myself didn't consider them as much when I got here a few years ago, but with time, obsevation and feedback now it's normal for me to do here without thinking. I'm not pulling them out of my @ss, and some people on here can recognize that. Maybe some people don't realize these things, as with the whole argument about wearing shorts, because they don't have that level of cultural awareness and connections here. I'm not trying to sound like I think I'm superior, just give my perspective...