I know where you are coming from with your theory on this - some do more harm than good !
Just do a search of some of the geek PC forums, MalwareBytes is one of the good guys along with Lavasofts Adaware and Spybot - Search and Destroy.
I have been building, repairing, overclocking
and generally fidling with computers since the advent of the 16k ZX Spectrum
Use it,its great.