Short answer: To avoid locksmith scams: get a price estimate before any work, be wary of a very low quote that balloons on site, verify the locksmith's identity and GPPKM membership, expect them to check proof of ownership, insist on a receipt, and walk away from anyone who pressures you or won't show credentials.
GPPublished by the GPPKM committee · a registered trade association. General guidance, not legal advice.