Yes, it is a donut tutorial...but you were saying you didnt want a dirty metal, but a metal with dirt on it...hence following that tutorial you could make a metail like I showed you, then add a checker texture for the dirt where you want it...

I guess whenever I do a tutorial I always just learn the steps and then change it all to make something that I need...it was just an example to get you on your way. No need to laugh at me taking time to help you solve your problems.