The industry typically uses a grading system: Grade A (Like New), Grade B (Minor Scratches), and Grade C (Visible Wear/Dents). For B2B resale, focus on Grade A or A- to minimize customer returns. You should demand a functional testing report covering the motherboard, screen pixels (checking for dead pixels), keyboard responsiveness, and all I/O ports. Ensure the supplier uses professional diagnostic software (like AIDA64 or BurnInTest) to stress-test the units for at least 2-4 hours before shipping.