I'm not sure that's always true. There are all-brick homes in SE DC that were once VERY desirable. Now... Well you can imagine, and the same is true in inner cities all over the country.
You might be surprized to see what those brick houses in SE are going for now in areas that you wouldn't have driven through 3-4 years ago. Trinidad in NE is the same. what you might have seen sell for 30K 4 years ago sells for 300k (at least did until this spring). DC is not a good example for what you are trying to say. Baltimore is.