In case you had any doubts that Washington is little more than a swamp with marble buildings, venture outside for a quick check on your surroundings. In fact, head to the intersection of 20th and L Streets, NW for a prime example. Much like a swamp, it totally smells like ass. Literal ass. You know that buttered popcorn smell they blow all over theme parks and movie theatres? Imagine that, but with raw sewage; it’s…