Most contractor disputes hinge on a single question: 'was that already there before I started?' Six photos before the pro arrives end the argument.
The six: (1) the workspace overall, (2) the closest 'before' shot of the actual problem, (3) walls and floors immediately adjacent, (4) any nearby fixtures (lights, switches, outlets), (5) any visible existing damage anywhere in the room, (6) the pro's arrival time on your phone clock.
Take all six on your phone, in the same minute, with timestamps. They're admissible in small-claims court if it ever gets that far — and the threat of producing them resolves 95%+ of disputes informally.
On HandyMandyMan, we encourage 'before' photos to be uploaded to the job thread itself. Both you and the pro have a permanent timestamped record.