I've been lucky buying most of my used cartridges, but yes it does involve some luck. I've bought a couple of used Koetsu stones that sounded just like a new one (now that I've had a new one to compare, and Koetsu rebuilds too) and have lasted a long time. I'm long done buying used cartridges, but a bit of a gamble helped get me into Koetsu at I time I would't have otherwise ($3K vs. $9K new).
You just need to "luck" out on a seller who cleans their stylus frequently, plays clean vinyl, runs proper alignment & VTF, avoids traumatic stylus incidents, reports hours honestly, doesn't hide issues like a skewed cantilever, low-rider, channel imbalance, etc :P The high-rollers that run a rotation of multiple high-end cartridges are good candidates. And unfortunately the audiogon market isn't what it once was for carts on offer (I rarely see Koetsu stones that look any good for a reasonable price).
But like others said -- at this point look at your table/arm first, and don't forget phono stage either!
You just need to "luck" out on a seller who cleans their stylus frequently, plays clean vinyl, runs proper alignment & VTF, avoids traumatic stylus incidents, reports hours honestly, doesn't hide issues like a skewed cantilever, low-rider, channel imbalance, etc :P The high-rollers that run a rotation of multiple high-end cartridges are good candidates. And unfortunately the audiogon market isn't what it once was for carts on offer (I rarely see Koetsu stones that look any good for a reasonable price).
But like others said -- at this point look at your table/arm first, and don't forget phono stage either!