Layers that are scale-dependent in the Layer List do not grey out, if you zoom out past the level they turn off. AGS JS TOC is an example for how to implement this.
This is not a bug as it does not prevent the widgets use or cause an error when using. It is more of an enhancement request that belongs on the Ideas page.
Also you may be interested in the code modification I have already code to allow for the grey out of layers not in visible range:
layers out of range greyed out
Robert that is awesome. I just downloaded and tested it in 1.2. It works. Perfect!