1. Does your gym have a suggestions box, where you could leave your suggestion about having the squat rack in front of the mirror instead? It's not likely they are going to see your complaint here
2. I don't find this weird at all *shrug* Maybe she got to the gym and found that she had left her trainers at home or at the office. I've done that before, and I've worked out in non-workout shoes. Or - shock horror! - the time when I left my leggings at the office, but really wanted to work out, so I did my lifting session in my jeans. I'm sure there was someone on a message board somewhere posting about the weird girl they saw lifting in her jeans (and let me just say, at first I was self-conscious, but then I thought MORE POWER TO ME for doing my planned work-out anyhow). There could be plenty of reasons she was on the stepper with her flip flops on - I doubt she just LIKES working out in flip flops.