You need to know if the neck is straight so looking along its length is a good place to start. Next, play an open string and then play it fretted at the twelfth fret. This should be an octave higher than the open note. Double check this by playing a harmonic note at the twelfth fret (lightly touching the string while plucking it should produce the same note as the fretted 12th fret note)
If it's a little out it could just be in need of a set-up but if it's miles out, leave it alone.
Next step would be to play single notes up each string, on each fret, listening for buzzes, rattles or flat spots.
If you're still happy that there's nothing fundamentally wrong with the guitar, get comfortable and sit and play it awhile. Does it feel balanced? Is the neck-shape comfortable in your hand? Does it make you want to play it?
In the end, it's all quite subjective so you it must make you feel good when you hold it or it will stand in the corner of your room gathering dust.
I hope you find what you're looking for.(It can take a lifetime!)