John Smith? Never heard of him.
On TV and radio cop shows, the detective sagaciously detects that a hotel guest has registered as "John Smith". The detective, gathering up his vast and famous and brilliant deductive powers, begins investigating to determine if "John Smith" might possibly be an alias.
This happens all the time in fiction.
Today I stopped to think. How does this compare with EXPERIENCE? I spent 5 years as a motel clerk in the '70s, so I do have actual experience in this area.
Half of the guests were 'shady', and maybe 1/5 of them were using the motel for criminal activities.
NONE of them ever signed "John Smith" or "John Doe". It's a safe bet that some names were fake, but none seemed suspicious.