If you spend much time on the Apple OS X and MacOS discussions I think you will find Etrecheck is far and above the most often used troubleshooting tool there. It has evolved significantly since its inception and while it neither fixes or even directly diagnoses any problems it provides a plethora of information for even a moderately informed user to spot potential problems.
Because of my predilection for running beta software I am always adding, deleting, updating and upgrading things on my computer. In spite of my best efforts at good computer housekeeping detritus does collect. I use Entrecheck prophylactically and I am frequently surprised at things it finds.
