As an employee of Guitar Center, I will say this as nicely as I can....
Sometimes, it's an amazing deal and can be an absolute pleasure. Sometimes, a mistake was clearly made and the gear isn't what it should/could be.
Your best bet is to call the store and speak with a manager and request somebody knowledgeable on the particular piece gear you're interested in. Used gear has a no questions asked 30 day return policy so even if you end up with something less than stellar, you're able to return it for a full refund.
I recommend, if you have a store local to you, go and meet someone face to face and have them call on your behalf regarding the gear. That way you have a name to a face and someone to assist sifting through our over 255 stores worth of used gear.
I hope this helps!