In the pilot episode of Person Of Interest, we first meet John Reese as a depressed, possibly suicidal, messed up tramp. He has long dirty and unkempt hair and old, ragged clothes.
After the incident on the subway where he beats up some thugs, he is released by the police and then contacted by Harold Finch and offered a job that uses his skill set. After hearing Finch's proposition he says he is not interested and walks away.
The next scene has him in a decent hotel room. He has now shaved, had a hair cut and is wearing respectable clothes. The transition is jarring.
He rejected the offer from Finch. So why did he get cleaned up?