It's not the hotel who hopes you don't notice; it's the event organizers. The costs for the convention (room rental, food, labor, set up fees, security, etc. etc.) are usually based on how much sleeping room revenue the event brings to the hotel. If the target is not reached, the sponsors may be on the hook for making up the shortfall, or incurring higher upfront charges. So, the hotel doesn't care if you are stiffing your own people. Somebody's gonna pay.