One of my jobs shows the starvation icon, because it is using a combination of labels (xx&&yy) which none of my slaves can fulfil (they are either xx OR yy labelled).

The context menu of that job says that all nodes of label "xx&&yy" are offline.

This is simply a lie. They are not offline. They do not exist. This is a huge difference and makes administrators unnecessarily search the whole farm to find that bogus offline clients...!