Did she say if it's all over or just in traffic lanes?
I'd take a guess it'd be most prevalent in front of the sofa etc, and then in the traffic lane from doorway to furniture.
I'd call this "bobbling"
My logic tells me it's more likely to be cause by "circular" forces rather than the "straight" movement impacted by a vacuum cleaner. It's normally where people scrub their feet around on the floor when they're sitting, or where a change in direction occurs in a traffic lane.
Have a quick go with her vacuum cleaner, I bet it isn't an upright, or if it is it'll be a poop one where the brush does nothing
