Quantity doesnt equal quality. A sold out dc show with a crowd that wont shut up at a show like Real Estate would be 100 times worse than a half full non talking (at least during sets) baltimore crowd. Crowd quality depends most on WHO is there, not how many people. Though dc can have good crowds, just depends on show/venue, same as Baltimore. DC crowds can either be people truly into music who want to support bands and listen to great music, OR (big ass or) people who just wanted to have a place to go so they can talk about their lives in public. Baltimore ones seem to me to be way more about the music. Baltimore shows are usually IMHO better than DC ones and 99 percent of the time, if I can choose between the cities to see a band, Baltimore wins. Good thing I live between the two, so i can make that choice. Walk, have you ever/do you ever, go to Baltimore shows?
All of this. I've experienced both good and bad crowds in both areas. A lot of it depends on the specific fans that either that band or venue tends to draw in.
Probably the most respectful audience I've ever witnessed was for Hammock, Stars Of The Lid & Christopher Willet which was at Iota. Basically, you could call that a DC crowd. You could have heard a pin drop at any point of that show. It was like God hand picked each person because they knew how to behave during a performance.
Both crowds at the Lyric in Baltimore for Pink Floyd way back in the early '70s were very well behaved but I suspect it helped that they were stoned and seated. This was just before all of the Bic flicking 'Rock 'n Roll!' burnout type ever heard of them and those type were always annoying wherever they were.