Does Trade Check use official values?
No. Scores and preference percentages come from the player; the result is a transparent decision aid.
What is a fair result?
The tool labels a ratio from 0.90 through 1.10 as roughly fair, but collection fit and confidence still matter.
Should a duplicate or collection gap matter?
Only as much as it matters to you. Both preferences default to 0% and can be adjusted from 0% to 25%.
How do I avoid a switched offer?
Stop whenever an offer changes and reread every visible item and quantity during the confirmation countdown.