It just means there's no perceptible odor.

These reactions can take place anywhere on the body. The face is the most common site, generally because things like lipstick or liquid foundation stay on the skin for longer periods of time.

The claims that cosmetics companies place on their products is practically unrestricted. Some claim they're dermatologist-tested, but that doesn't mean the product has passed the test with a viable number of people. There's simply no guarantee.

...his sleep, though deep as death itself, was not dreamless this time, but threaded with ghostly wisps of dreams. These wisps were clearly recognizable as scraps of odors. At first they merely floated in thin threads past Grenouille's nose, but then they grew thicker, more cloudlike. And now it seemed as if he were standing in the middle of a moor from which fog was rising. The fog slowly climbed higher. Soon Grenouille was completely wrapped in fog, saturated with fog, and it seemed he could not get his breath for the foggy vapor. If he did not want to suffocate, he would have to breathe the fog in. And the fog was, as noted, an odor. And Grenouille knew what kind of odor. The fog ws his own odor. His, Grenouille's, own body odor was the fog.

And the awful thing was that Grenouille, although he knew that his odor was his odor, could not smell it. Virtually drowning in himself, he could not for the life of him smell himself!

Odor Eaters

The only way we're going to get rid of the odor is for them to get everything out of there.