[Entaroadun]

There's actually quite a lot of little details that get speculated on in SEM. The fact is, until you test it yourself, you won't know for sure. One interesting thing about QS for phrase and broad is that the QS you see is not the real QS; it is only the QS for queries that match exactly to your keyword. The real QS is weighted appropriately, based on impression distribution.

[rfergie]

I also doubt that quality score takes only integral values.

QS as reported in the interface is a bit like tool bar page rank; it can tell you if you're doing really well or really badly but at the end of the day your competitors probably have a load of 7's too

[dminor]

This was directly from a Google Adwords rep.

[wildwood]

Google AdWords reps are far from authoritative.