Asians, Northern Africans and Latinos
The English language is full of neutral and derogatory names for people of all races and ethnicities. To start with negative epithets, speaking of people from Asia Minor, the term sand nigger refers to people from areas in the Middle-East, the Arabian Peninsula and northern Africa where there are large deserts. Carrying the same derogatory implication as sand nigger, the word towelhead, furthermore, is meant to describe people who wear turbans or similar headwear in areas such as Africa, the Middle-East, Afghanistan and India. A few Americans, when they are really angry at something related to people from northern Africa or the Middle-East, may utter words like sand nigger and towelhead, contrasting the fact that Americans in general are very accepting of people with different ethnicities and physical attributes.
Continuing with epithets for Asian people, the word Chinaman was once more or less an accepted name for people from China but has fallen out of fashion and is now considered rude. A person from China, nowadays, is simply called a Chinese person. In the same way, the accepted classification of other people from Asia and northern Africa is to call them by a name strictly linked to their national background or country of residence. Labels such as Africans, northern Africans, Asians, Saudis, Middle-Easterners, Afghans and Indians would all work well for this purpose.
Americans from Latin America
Americans whose families originate in Central or South America are usually referred to as Hispanics or Latinos. Both terms are relatively neutral and frequently used interchangeably. One difference, though, is that the term Hispanic often implies having a Spanish-speaking family background and the term Latino indicates ancestry anywhere in Central or South America, including Portuguese-speaking Brazil. Another difference in daily usage of the two terms is that Latino tends to be used in the western United States while Hispanic is commonly applied in Florida.
Interestingly, the word spic, which looks like a harmless short form for Hispanic, is considered an offensive racial slur against people of Spanish-speaking or Latin American descent. Another offensive word for Latino is taco head, usually used to refer to people of Mexican descent. Neither of the words spic and taco head — nor indeed any other negative epithet — obviously, should be used if you want to treat people with respect.