Interesting blog post here from SFGate. Definitely made me think back to all the various disgusting things I've witnessed while waiting for the shuttle connection near Civic Center BART station.
I can make a long list here but instead, I've somehow selected the three worst observations and here they are!
#3 Homeless man lying in his own urine
#2 The poor dog of a homeless man licking up blood from bird carcass on the sidewalk
#1 Pigeons fighting over a pile of human feces
Got worse ones? Please share!