Not sure on the ATVs but the biggest thing with sleds is to look them over good, you will know if the sled was totally beat on from knicks and dings that you can pretty easily see. Also make sure the hood lines up well when closed if it doesn’t the sled may have been in a wreck. Also look for something that is ALL STOCK, people can say upgrades were done by a dealer but you never know unless they have receipts to back them up. Not to mention performance parts are typically “go fast” parts so probably want to avoid those sleds.
Sleds are a hoot to ride and they will pile up WAY more miles than a wheeler. Not uncommon to put 600+ miles on a sled over a 3 day weekend.
The newer the sled the less miles are an issue provided the sled wasn’t beat on. They are making them so good now people are getting 7-10k miles without too much trouble.