ALL tuners make mistakes any that say otherwise are liars, they would not be human if they didn't, if one told mne her never had I would not use him as I would not trust him.
The trouble is with reputations you only get a one sided story, the bad side mostly, other things are beyond the control of the tuner eg if a brand new component fails shortly after fitting, as some do, especially electrical ones, the tuner gets blamed.
We just have to hope they are silly mistakes, that are soon sorted and cause no damage.
My fave tuner started at age 14 tinkering with cars/bikes etc, and to date he is just himself and one other, and he is like nearly 70!!
tabetha