That would suck.

Anyway you could either slow down to reduce the sweat or freshen up before you get on BART? Maybe just quick wipe down in a restroom and a shot of deodorant? It might help to take a shower before your ride even though you know you're going to end up sweating anyway.

I don't have a train ride to deal with but I bring my clothes in with me to work every day and change there. I leave a set of nice shoes at the office so I don't have to bring them along.

A few jobs ago I used to take a 50 minute bus ride into work on most days and would just ride once in awhile. I actually don't mind taking public transportation. I could get some reading done or take a little nap. I was one of the first ones on the bus though and I could always get a seat. It's not so great if you have to stand 45 minutes but an audio book or even reading a smart phone can be done while standing to help make time pass.