What’s a proper diagnostic?

A mechanic that can identify the difference between secondary bi-product codes and codes that directly identify the problem, (example) when you have multiple more cylinder misfire codes vs only 1, this suggests a plugged fuel filter.

Asking customers the correct questions and listening

Usually the customer knows the answers but don't know it! Getting the history of what it is they have an issue with can casually speed up repair time.

Badass mechanic technicians are not just everyday mechanics

To be a Mechanic @ Badass Mechanic, you must be a master in all fields mobile. Mechanical issues are only one of the many issues people run into. Electrical, Hydraulic, Pneumatic, Refrigeration, AC and of coarse the typical solenoid. One has to have keen eyes, ears and trust instinct and wisdom to resolve the many issues we face especially on RV's and Motorhomes.