How can I tell if an exchange is a scam before depositing?

Checklist before depositing a cent:

1. CoinGecko/CoinMarketCap presence with non-zero, non-faked volume and a 'trust score' from a known auditor.
2. Proof of reserves — Merkle-tree audited and recent.
3. Regulatory status — search the exchange name on your national regulator's register.
4. Domain age — less than 2 years is a red flag.
5. Search the exchange name plus 'scam', 'withdrawal', 'frozen' on Reddit, Twitter, and Trustpilot. Universal complaints about withdrawals are a 100% certain scam signal.
6. Withdrawal test — deposit a small amount, trade, withdraw. Real exchanges process; scam exchanges introduce 'verification fees'.

If in doubt, stick to top-10 venues. The yield advantage from obscure exchanges is rarely worth the counterparty risk.