Most of mine aren't due to penny pinching to be fair, they've just been to sh1t garages that don't know their arse from their elbow (or more likely just chuck stuff together as quickly as possible).
Seen it time and time again where people spend good money and get a poor outcome. I can see why the motor trade all gets painted with the same brush to be honest.
Worse case is they have to pay twice to have the job done properly..
^This^
Where I am working in Barnes at the moment (long standing customers). I find myself frequently coming across eff ups made by their stupid builders. The customers aren't tight, they just don't pay sufficient attention to the work being done (or don't understand the difference).
Fortunately, now I am charging them by the hour/task so I am no longer out of pocket but I have been there for 8 months since Nov 2020 and increasingly risk annoying my other customers by not being available.
I hate seeing decent people being charged premium rates for substandard work. I hate seeing anyone receive poor quality but when the customer is a tight wad, I have less sympathy.