One thing on BART that you may not want to have a bird's eye view of, but you do, is hair!
As a standing passenger, you see pretty clearly how clean someone's hair is, whether they have dandruff, whether they are balding, how they are covering their bald spots, and when they are long overdue for a cut or color job.
A couple noteworthy observations I want to point out here. I see two trends in bald (or balding) men. The first is those who do whatever they can to cover up the bald spot by growing their hair long, and covering the spot with it. It looks ridiculous. One man that I won't ever forget has a handful of hair that is about 6 inches long, that goes from his right temple to his left. It does a poor job covering his baldness as the skin is quite evident and frankly, it looks very sad and pathetic, that someone finds it that difficult to accept baldness.
The second trend is those who shave their heads or keep it at a very short length so the bald spot just blends in. I much more prefer this trend. It looks cleaner and people just don't laugh at you behind your back!
There are, of course, still people who wear toupees. That, by far is the MOST ridiculous, and thankfully, a dying practice. I once saw an older man who has some natural hair left around his ears that were gray, but awkwardly positioned on top of his head is a dark brown toupee!! It was so ridiculous looking and out of place that everyone who passed by him gave a second glance.
To all bald or balding men out there, you should definitely accept baldness gracefully and tastefully bcause there really is nothing wrong with being bald! Unless you can afford a hair transplant and deal with the pain, keep your hair short, or shave it, and be proud!