This is actually one of those things I thought about a lot while riding the red line metro to and from work each week.
I've noticed that among other things, there seem to be a couple of metro drivers who like to operate the trains at speeds as fast as possible between stops, rather than just pacing it more sensibly. They'll rapidly accelerate, headed westbound out of a station like the Bethesda or Friendship Heights location, only to wind up stopping in the middle of the track someplace before the White Flint stop because they have to "wait for another train directly in front of them".
I've also experienced the trains that always seem to stop short of a station and then jerkily move into position before opening the doors. I can understand the problem if all of the trains really do behave differently and drivers have to get used to differences between each one. But there are definitely other times I take the train and it's very consistent in speed and smooth at every single stop.
Another oddity I've noticed with the DC red line is the fact that only Verizon customers get cellular service while the train is in the tunnels. All other carriers lose signal until the trains get back outside. (I'm told this is due to some old, outdated exclusive contract Verizon made with them to wire up the tunnels. It was since struck down as illegal so all carriers can now add service there -- but apparently none have been interested in spending the money to do so, yet.)
And as for the people talking about thugs and crime on the metro? I have to say, I've honestly not experienced much of that. I'm sure things are a bit different if you're taking the train late at night on a weekend after hitting the bars or clubs. But at least during the rush hours for commuters, I see practically everyone using a tablet or smartphone, or even a laptop on the train -- and have yet to see one get snatched out of someone's hands.
The only crazy issue I ran into was this 20-something guy who got on a train in the morning with a radio in his shirt pocket blasting loud, annoying techno music. At first, I don't think most people pinpointed where it was coming from and patiently waited for whoever it was to realize their headphone plug came loose or what-not. Then we started figuring out the guy had no earphones and was doing this on purpose. A guy sitting beside me who was trying to read a book asked the guy, politely, if he could turn the music down -- and the guy got all aggressive, challenging us to fight with him if we didn't like it and calling us all "lemmings" and so on.
(I told him his lousy techno soundtrack wasn't even worth fighting over.) This went on for several stops until he finally ran off the train at the Medical Center stop. Like someone else posted above, it doesn't seem like the posted rules (No eating/drinking on the train, no music players without use of headsets etc.) get enforced very well.