Buying a used Mac: Guide

Image source: www.pearltrees.com/td2quentingallez/item125663023

Checklist:
- scratches and dents
- serial number
- speakers, headphone and microphone (and side ports)
- charger
- keyboard
- webcam
- screen

Programs recommended:
Blackmagic Disk Speed Test (free)
Coconut Battery (free, web) or Battery Health (free) or Battery Monitor (free)
Screen Utility (free)

Generally recommended:
Grand Perspective (free, web)