CleanMyMac acts like a virus itself [edit: this is an opinion; it’s not an actual virus] and I would never, ever install it on any of my Macs. It’s one of the few things I’ve disagreed with MacSparky about over the years. I can’t recommend it to anyone.
If you need customization, use Onyx. If you want to clean up the crap after install, use AppCleaner or AppDelete or AppCleaner & Uninstaller.
No. Just no. Expensive. Yes. A virus or malware? No. Do not confuse it with MacKeeper.
And many more posts about that in this community and all over the internet.
I am a new user here but a veteran mac power user 
I probably should have been more clear. CleanMyMac is slow, bloated and has constant memory leaks using a gig of RAM. It also insists on having its background process run no matter what.
I’m not referring to MacKeeper, it’s really CMM that I find quite repulsive. Virus is a strong word, but I wouldn’t touch that app with a 50 foot pole.
Very interesting opinion! Thank you for your clarification regarding CleanMyMac not being a virus. Because that really might confuse some people.
I am not using CleanMyMac any longer (too expensive for my use cases). I can only say that I was quite pleased as long as I had been using the application. Which I did for quite some years on several Macs.
No issues whatsoever, no memory leaks, nothing. 