I never booted anyone from my room but I almost had to. I was waiting for someone to come get credits from my kiosk for a trade and the girl went AFK. I wrote that I might have to boot her so that I could close off my room but she returned before then.
I have been booted a few times. I've entered quest rooms that weren't finished and most of the time I've been asked to leave because it wasn't complete. Other times, I'm just automatically booted. The first time it happened, I was so surprised because all I did was enter the room. However, I guess I understand if the owner of the room needs you out of the room pronto instead of asking you to leave.
Booting gives room owners some sense of control. Even if it is done for "right" or "wrong" reason, in your opinion, technically it is the owner's room. If anyone is offended by booting, just remember that the owner is booting the virtual you, not the real you.