Just to followup on this: make sure you have foot IK previewing on in the animation window when having an animation file selected. While most animations with the default unity model won't float, some will look better with the preview on.
.. I don't see how floating a little is 'scuffed'. If your model is floating above the ground during an animation preview, that usually means the model has an origin point that is not at ******** of its feet, or that its feet are by default posed in such a way that the feet are not flat on the ground. It's not a problem with my animations.
