Having purchased 9 used cartridges here on Agon (and 1 on ebay), I can attest that it is no more risky than other used component purchases. Feedback check is essential here. I have received one cartridge that was not as described (and no, it wasn't the one from ebay believe it or not). On the other hand I have received a few components (mainly power amps) delivered with shipping damage. I am more leery of having heavy items shipped than buying used cartridges. Buying anything used is always more risky but overall I think well worth it. As far as how many hours the seller claims his cart to have, I only use this as a guide, not realistic unless he claims to have logged hours. I think most sellers here on Agon are pretty staight forward.