I would add trying to find a plumber or electrician you have to be very selective cause they may rob you.
You get what you pay for.
If you live in a high quality building with porteros, cameras and alarms, its unlikely they would attempt so.
If you hire high quality technicians with high "aranceles" and pay well, it is unlikely they would try anything strange.
If you join forums like this others or the others which are on facebook. Then you ask for recommendations, you would come across "usually" trusted recommendations. I use the word "usually" with caution, because one time, I had hired a maid on recommendation of a stranger on facebook forum and that maid robbed me of my cutlery in small doses till I became aware. Nothing too violent or bizarre. But no one can be trusted. A little bit of common sense, learning body language, using self awareness and awareness of people ( not only what they say) but their tone, facial expressions, body language will make it easy to detect potential criminals.