To answer my own question and possibly inform anyone else who has happened to have searched to this topic:
I noticed that all the 141 girls have CCTV and they're generally a screen split with four cameras. Usually, there's one of the elevator/stairwell, one of the hallway in front of their room, and one or two at the door. Basically, as soon as your on the floor, they see you. Saunas also have CCTV, but I have no idea if the girls there watch.
I found that the cameras were rather helpful. I was on my first trip to HK, so I was uncomfortable walking down a hallway and ringing random doors. So, I found that if the floor isn't too busy and you wander around a bit or stop at a door for a few seconds, some girls will open their doors and invite you in (if they like what they see). It made it easier to turn down a girl because I didn't feel that I had bothered them by ringing a door bell and I could just tell them I was looking for someone else. This method worked great for me... besides, getting invited in is much for fun.