The operative concept in a floor covering installation is that it is 3 Dimensional, not flat. When a sub-floor undulates (a rolling hill and valley) it can ruin a flooring installation. It is natural to have a certain amount of undulation in a concrete slab (either below, on, or above grade). American National Standards (ANSI), The American Institute of Architecture (A.I.A.), and each material industry association, publishes the appropriate tolerance for flatness, as a slope or level.
The damage to the floor will depend on the materials used. A resilient floor (rubber or vinyl) can wear excessively, and if it is a tile the seams will not line up.
The effect on a wood floor will depend on whether it is a glue-down or nail-down installation. In a nail-down you can have excessive flex, manifested as squeaking, or bouncing under foot. In a glue-down installation, the boards can de-bond and loosen (more likely in engineered wood than solid wood).
The floor-covering contractor is told to evaluate the site condition prior to the installation of any flooring, and prepare a plan to flatten the sub-floor, whether it be Hardwood, Sheet Vinyl, Vinyl Tile, Linoleum, Cork, Rubber, or Carpet.
Key: Hardwood, engineered wood, solid wood, Sheet Vinyl, Vinyl Tile, Linoleum, Cork flooring, Rubber flooring, Carpet, flatness, level.