some of the hazards to the walkups:
1. places with lots of product on different floors and you have to go up and down the stairwell - dirty and smelly
2. using the stairs in the summer - very sweaty (I am a big hairy gwailo)
3. waiting for dodgy and slow moving lifts (and worrying I will get stuck in one).
and the biggest hazard to the walkup:
running into all you ugly mongerers doing the same thing!
seriously, there have never been any problems provided you are "law abiding" i.e., be nice to the girls, pay them properly (even if you think you are cheated by lousy service).