The way to see if a guitar is any good(correctly) has little actual playing involved.First check the specs...make shure they meet what your looking for.Check the guitar for cracks,chipping,orange-peel and inconsistancies in the finish.Next check the neck to make certain its not warped by looking down the fretboard with the bridge at eye level.Check over hardware for any flaws.Look over the fret/inlay work as well.

finally...bend some notes on all strings to assess tuning stability and check for fret buzz.
Obviously you want the guitar to 'feel' good too.

No need to play any song...