This is something that happened to me a few years ago, but I'd be interested to hear others' take on it:
At the time, I was interning at a small museum. The museum was a cash-strapped nonprofit, and in order to bring in some income, the director decided to rent out some of the extra office space. This director was a very strange person who didn't always make the best decisions (for example, she would bring her 150-pound dog into work every day and let him wander around the museum floor). She ended up renting out the space to a photographer who, as one staff member politely put it to me, "took pictures of wives to send to their army husbands".
I was completely horrified by this arrangement - to me, it seemed totally inappropriate to have some guy doing photographs sans clothing in a public space that was supposed to serve the community. It was also a little unsettling to be trying to work in the office space while knowing that someone was disrobing and doing suggestive poses a few rooms away. The director, however, had no problem with this guy as long as he paid rent - in fact, she claimed that he was doing a "good service for the community" because there was a large army base in town.
Well, one day I was doing a toddler program in the museum. There was only one set of bathrooms in the entire building, which were situated on the far side of the toddler area. In the middle of the program, the doors to the office space swung open and a women wearing nothing but sneakers and a short robe came out and walked through the length of the toddler area to the bathrooms. The parents who were there all stared at her in disbelief - it was painfully obvious that she wasn't wearing anything under her robe - and then swiveled their heads around to me. One of them asked me what was going on. Caught on the spot, I couldn't come up with a viable excuse as to why this woman was in the museum, so I stammered out the truth. The rest of my program was incredibly uncomfortable, and I noticed that most of those parents didn't return the next week.
Anyway, I told one of the staff members what had happened and she seemed rather angry - apparently the photographer had been told that if any of these women needed to use the bathroom they had to come down fully clothed. Nothing happened though - this guy continued to rent the office space and carry on his business. I'm wondering now, though, if I should have done anything different in this situation - specifically, what should I have told these parents? Should I have alerted a museum board member (one of the other interns was staying in a a board member's home)? Should I have spoken to the bathroom-using woman myself?