I've heard that if a guitar sounds good un-plugged, it's gonna be a good sounding guitar when it's plugged in.

 I think it's a good sign, if an electric sounds good unplugged,

but it's not proof of a good/bad sounding guitar under other

conditions, the attack/sustain characteristics can be very different

plugged in, particulary on semi-hollow guitars, which always sound

'good' without an amp.

Then again, most of the guitars that I think sound particularly good, sound

that way without an amp too...

As always, your mileage may vary.