Yeah that's the risk, that's why if you receive coins from P2P trade or not from centralized exchanges, you have to use it in private ways too. Either you sell via P2P or you buy a gift card which not require any identity.
1. Use AML tools. Some are free others cost money. You can analyze the coin you received before making a transfer, or you can ask to analyze the coin before the P2P transactions.
What if the seller not want to give his address or doing what you ask? remember finding people who want to trade via P2P is already hard, while you're making it harder.
2. Decentralized mixing like JoinMarket. Without even knowing if the coins are problematic, you can send them into mixing and hope you get good ones.
You make the situation worse, many centralized exchanges not want to accept tainted coins.
If you don't trust someone due to the assumed risk that you think surrounds the person, then you don't have to trade with them, your concern is easily avoidable when you don't even trade with the person that you scared about the genuineness of the coins they are sending to you.
In money's world, there's nothing called trust.
Your best friend that you know was good in school, then he ask for money with a purpose for surviving, but the reality he use for gambling. No one knows, people will try as best as possible to convince you to believe them.