I would check to see at some of the online bow stores for last year's models. These would be new bows that would be heavily discounted. Then check to see which bows come with a lifetime guarantee. If you were able to buy an older bow, I think you would be happier with one of last year's models than one that has been used. I think that would probably take a lot of the fear factor out of it for you.
Additionally, buy the best sights, string release, and arrow rest's that you can afford. Even if you were interested in bow hunting again, you could pull these "accessories" off of the older bow, when you decide to update to a new bow.
If you are dead set on acquiring someone else's bow, then check the local "buy, sell, trades", that are often filled with used sporting equipment, and these might include bows. Also, do not be afraid to ask the guy if you can shoot what he has, just to get a feel for what you will be purchasing. You might also get some decent arrows out of it, if he is moving and just needs the cash. Then take that bow, if you decide to buy it, to a competent bow shop to have it gone over once, for new strings and an idea of what poundage it is set at.
Buying a used bow at a competent archery shop would be better, because then you should be able to find out if the guy abused it, and if the dealer feels that your purchase is a good one. Most shops are very concerned about bad publicity, and so they won't sell you something that would reflect badly on them.
But realize that most bows that are warranted for a lifetime guarantee, are only sold as such to the original owner. So consider asking him to send it back to whomever made it for a tune up. Offer to pay for the shipping, and that way, you butt is covered.
Hope that this helps.