Mites are usually quite visible to the naked eye, but a check for parasites might be in order and at the same time they can look for mites. If it's wild caught, you can most likely be pretty sure you'll have both. If you take it where your other snakes are, be sure to keep it in a seperate room if possible for 3-6 months as a quarantine. In the meantime, check for general look of health. Shiny scales (unless it's preshed) good weight, and active.