I retired from Motel 6 as a night auditor, and also worked for EconoLodge, Days Inn and Super 8.
Some of these establishments actually give priority to walk-ins who do not have a reservation, as it's never known if a reservation is going to turn up until they actually arrive. On an Interstate highway in the midst of the week, long haul truckers will drive until they can go no further, then stop at the nearest motel for a rest and shower.
Many times, I checked in girls who just wanted a night or weekend away to party (If they wanted to dance in their rooms, I'd place them on the ground floor away from other guests.
Always a good idea to anonymously call an establishment to find out what their quiet times of the week and year are for future reference information.
Simply wanting to get away is never cause for suspicion.
We had "unsecured" reservations at Motel 6, rooms which could be reserved without a credit card until 6:00 PM, when the French Accor Hospitality Corporation owned and operated the chain. On numerous quiet nights, the majority of guests I checked in were unreserved walk-ins.
Nobody was ever suspicious of any check-in, unless it was a previous guest who had caused trouble or misbehaved. Those people would often be barred from future stays, but then they'd simply go to other competitors in town, and competitors tend to not share information with other establishments.
Pets were allowed at Motel 6 and EconoLodge, so dog shit was a common mess for housekeepers to clean up. Also, half of the rooms at Motel 6 in 2002 were rooms where smoking was permitted.
Keep in mind that these are customer service agencies who are trying to make money by selling rooms, they are not the police, and you do not work for them. Just do not be abusive.
Every motel I ever worked at had suicide cases inside their establishments, three had recent armed robberies, and other various crimes and hijinks can occur.
Often, an arrival will ask if they can have a quiet room away from everybody else, not wanting to be bothered. I would accommodate them if I could, as I worked for the guests, not the housekeepers who would have liked to have all the occupied rooms neighboring one another for cleaning convenience. It wasn't unusual for an exhausted guest to trudge in off a long drive to check in at 3:00 AM.
For guests who have checked in and paid for multiple nights, doors can be locked from the inside, and the universal "DO NOT DISTURB!" placard hung from the door knob will assure that housekeepers and other staff will leave you alone until after you should have checked out.
Rarely, a scared and abused local would check in to get away from a bad home situation. As clerks, that is none of our damned business, and if we were to call the police or emergency services in those situations, we would have been fired. The guest is the boss, and the discretion of whether or not to call anybody from their rooms is entirely up to them. If girls under the age of 21 rent a room for smoking pot or drinking alcohol, we are to give them the benefit of a doubt if we do not know that for a fact. One inexperienced stupid old schoolmarm hag clerk trainee wrongly assumed a party of teenage girls who rented rooms were indeed drinking alcohol and doing drugs, so she stupidly called in the police. As it turned out, those girls were Mormon missionaries, and that clerk was summarily fired, never to return to the field of customer service again, and those girls were given those rooms free by the apologetic manager to avoid disastrous publicity when that motel was struggling a bit.