I think they are just people, folks like everyone else. Come to think of it, this is one topic that gets it's fair share of debate every now and then. But I honestly do not see why we should even engage on debates like this.
Tattoos are almost as old as man himself, though they weren't known as tattoos till the 18th century. The word was derived from another Samoan word, Tatau, meaning to strike. Before then, the most common words which is still in use till date, is tribal marks.
Although tribal marks seems like an act of the past, they were once invoke. They were used as sacrifications for specifically identifying and beautifying the face or body. Almost every known cultured civilization in the world before us inscribed different types of marks on their bodies. The Egyptians had several types of tattoos, so were the Persians, samarians, the native Americans, as well as almost the entire Africans.
Only when we get sentimental, will we judge. Tattoos today are no different from tribal marks. The vast majority of people who have them today, do it under the name of art. A very few percentage use it for identification, people who belong to certain gangs or societal cults. Even important organizations use some form of tattoos for identifying one and another. An example will be the special forces unit in the military. Most of them have distinctive and unique tattoos. Hence, i see no reason why tattooed skin people should be judged negatively in anyway.