Of course you should use them with caution. Used inappropriately they will damage your system. I use Onyx which is freeware, has been around seemingly forever and is updated frequently.
I see that in Isaiah’s post that you quote he says:
“Some of the cleaning apps are pretty good – CleanMyMac by MacPaw gets consistently great reviews and the MacPaw guys are (inserts thumbs up emoji x2)”
No but I do know for a fact that Apple has specific procedures for computers that are brought in with these types of apps installed on them. As Teefers has mentioned they don’t have to be malware to cause harm. The bottom line is it’s your computer, use whatever you want on it as long as you are responsible for what happens afterward. Personally I have seen enough to have decided to never install such apps on any of my computers. Same goes for anything made by Norton. BTW, Onyx and cleanmymac are not considered the same type of app. I would trust Onyx much more than I would ever trust an app like cleanmymac, but again, do as you wish, it’s your data :)