You can tell if Jordan 9 are fake via the size tag. If the text over there is too thick or so thin it looks like it’s scratched, you’re 100% looking at a fake pair.
Air Jordan 9 fake vs real guides for individual items
Download the Legit Check App By Ch on iOS/Android to have the full encyclopedia of fake vs real guides in your pocket. With a few clicks, you’ll access the relevant part of a guide.