Specifically, beta readers. Those folks who serve as our frontline critiquers (or "critters" as some call them.)
I've heard people say that you shouldn't use friends and family members as betas.
"They'll just sugar-coat their reactions. Tell you what you want to hear."
That my be true for some.
But not so in my case.
My Wife is my beta. Once I've written, revised, and polished a piece, I hand it to her and say "Have a read and let me know what you think."
You're probably thinking: "Yeah, she'll tell you how great you are, how it's the best thing she's read ever."
Sure, she'll tell me what bits she liked. But she'll also crucify me for things like passive voice, plot inconsistencies, and bad clichés, among others.
And she can be harsh.
I find if I can entertain her with a story, I'm on the right track.