Hardened valve seats - do they really matter?

People don't realize what the main cause is for sunken valves due to beat out seats. It's running a dirty air filter for extended periods. The dirt, dust and grit grinds exhaust seats to pieces. Valve seat recession. Dust and dirt in the incoming air fuel mixture is the #1 cause. What do you think a machinist is going to tell you? That's like asking a hooker if you need her for a night.