Sometimes they are badly refurbished originals no longer meeting quality standards, sometimes they are just fake. Tons of low-quality bearings are labeled with false brand markings to justify a higher price.
They look like, and are marketed as, genuine, premium brand products. Even the packaging is skillfully imitated. So let’s face it: fake bearings are difficult to detect. They won’t be scratched, rusty or dirty.
They won’t necessarily even be cheaper. But still, beware of those “too good to be true” prices that are below market value and have unusual availability.