Bumping an old thread but I had my first experience with dayuse recently and it was very positive. Made the booking online about 10am for a 1pm check in. Double checked the hotel to confirm they'd got the reservation. It was at a "boutique" hotel so a tiny tiny reception and so obvious what was going on as I passed the same receptionist with the girl in tow about 20 mins after I'd checked in. But it takes you 1 second to pass the reception area so who gives a shit.
Paid in cash, didnt ask for any id. I imagine bigger hotels may require this. On checkout, the receptionist wasnt there so I just left the key card on the front desk. Very easy, 6 hours for a very clean hotel room in London for less than 50 squid.