[sk5t]

Perhaps if the person being weighed jumps around, in which case the scale is doing its job correctly--or a very sensitive scale reacting to changes in air pressure. Scale readings generally do not jiggle/bounce with a static load.

[Retric]

After standing on a scale and you get oscillations from momentum which soon resolve to your actual weight. You see the same thing when putting fruit on a scale at the grocery store.

You can see similar issues with most purely mechanical dials to one degree or another when they are responding to a rapid change.

[majewsky]

But that's a bug, not a feature.