Is it OK to buy a used turbo?

Could you elaborate on the risks and considerations when purchasing a used turbocharger? Are there any specific checks or inspections that should be done prior to making the purchase? What are the common issues that arise with used turbos, and how can they be mitigated? Is it generally advisable to opt for a new turbocharger instead, or does a properly refurbished and inspected used turbo provide comparable performance? Also, how much can a buyer typically expect to save by going with a used option? I'm particularly interested in the long-term reliability and maintenance requirements of both options.