A traveller arrives in a small town and decides he wants to get a haircut. There are only two barbershops in town - one on East Street and one on West Street. The East Street barbershop is a mess, and the barber has the worst haircut the traveller has ever seen. The West Street barbershop is neat and clean, its barber's hair looks as good as a movie star's.
Which barbershop does the traveller go to for his haircut, and why?

The traveler goes to have his hair cut at the barbershop on East Street. He figures that since there are only two barbershops in town the East Street barber must have his hair cut by the West Street barber and vice versa. So if the traveler wants to look as good as the West Street barber (the one with the good haircut), he'd better go to the man who cuts the West Street barber's hair - the East Street barber.
By the way, the reason the West Street barbershop is so clean and neat is that it seldom gets cut.