Used cards are always a gamble and a lot like buying used cars. Sometimes you get very lucky and other times there is always something that needs to be fixed. The gtx460 is a odd card, if the original owner ran it at stock fan speeds in a hot case but overclocked it like crazy it isn't worth it. These cards have issues with the power vrm overheating if there is no heatsink to cool it and the memory doesn't like getting hot so people have issues. I got one and using it now, its almost two years old but it is modded and is rock solid.
You can mod one pretty easily in under 15min and likely it will last a good two or three years.