Three teenage carol singers toured Southsea saying they were collecting money for charity.
The lying trio made the wrong choice when they knocked on the door of 79-year-old Len McDonald.
The pensioner was surprised when he heard the teenagers were collecting cash in aid of the blind.
He was on the executive committee of the Portsmouth association for the blind which had no licence to collect door-to-door.
Richard Cook, the chairman of the Portsmouth association for the blind, said people doing this were effectively stealing money from charity.
He said: ‘If people think they have already given money they are less likely to help genuine collectors.’