Tuner

how to know or tuner doing well job?

Does the fueling stay on target?

Does the engine start easily in all conditions (hot, cold, high altitude, low altitude)?

Does it run smoothly?

And finally, does it make the expected power?

Reasonable fuel consumption also would be an indication of good job. Many tuners mostly concentrate on wot tuning and never bother with transition and part throttle mode which is a big chunk of excessive fuel consumption.