I've never understood what people mean when they say public transportation is "dirty". I've never had to sit or stand in or near muck or sick or anything like that. If there's a bit of grime in the corner or animals or something... Okay? I don't have to touch any of that. I care about as much as getting onto a slightly groady amusement park ride, or seeing bugs or squirrels in the park; it's not going to so traumatize me that I won't ride. Is it the people? I've had to sit next to one or two people who smelled in my hundreds of train and bus trips. Or is it an ethnic/class dogwhistle sort of thing?