Used Acoustic Guitars
The main things to look for in used acoustic guitars are body style, electronics, neck, intonation, tone wood, bridge, fingerboard and finish. These guitars come in various sizes from travel sizes to Jumbo sizes and the dreadnought. You have to see against ease of playing compared to tonal quality. There are guitars made with a preamp so the sound can be amplified in a big stadium or other venue. The neck size depends on the size of your hand. It has to have the right intonation to play right.
Basically used acoustic guitars have to be in tune. The wood used to make the guitar has to suit your playing. Make Sure the tuning machine on your guitar is right. Enclosed machine heads do not require as much maintenance as open ones. The bridge and fingerboard have to be in good condition and the finish has to be something you like.