Do you know how to check the "action"? It is basically how much you have to press a string down to engage "to a fret". Too close and your guitar will buzz. Too far and you have to pull down the strings a lot which is bad too. Do some scales or arpeggios on a few places (1st fret, 6th fret, 12th fret) on the guitar to check for "action".
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Do some bar chords ("E form" and "A form") up and down the neck.
See if the "E" note on the 12th fret is the same "note" as the "E" "open". This is easy to check with a guitar tuner. Not a super biggie if they don't match.. could require bridge adjustments to make that right.
Look straight down the neck to see if the frets line up nicely.
How does it feel to you?
Ah, heck, for a hundred bucks... just buy it.
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You are probably more likely to get a better value from a private party but you'll also be taking more risk (no music shop to go back and complain to).
Most important of all, have fun
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