OK, I've read the threads about tipping the hotel maid, parking valet, and at buffets, now what about tipping the bathroom attendant? Should I really give him a dollar each time (which can be quite a few times) when all he does is turn on the water for me and hand me a paper towel when I'm done? Or am I tipping him for keeping the place clean? I understand that his is not a pleasant job. Comments?

There's most definitely a volume discount, Mel.
One visit per 4 hour time interval warrants a $1 tip.
Two visits per 4 hours requires a tip and a smile and "thank you".
Three visits in 4 hours is a $2 tip total, which you may dole out all at once with the first trip if you know you'll be back again twice more.
Four trips requires a $2 tip plus a discreet word of explanation as to why you're back and forth so often such as, "Gee, that coffee sure is strong this morning", or, "Hopefully this burning and penile discharge will ease up once my antibiotics start to kick in".

I seriously hate those bathroom attendants and I try to take the biggest, smelliest, sloppiest, loudest, drippiest, sweatiest dumps just to piss (pun intended) them off.

I typically tip about $10 the first time.

The next time I take a poo the attendant will give me A+ service including wiping, washing, and de-dripping. It's well worth it.

Obviously you're living in the San Francisco area, eh curious?