Calling them "cheat sheets" is a cop-out. It implies that what matters is that people listening to you are going to sneer at you because they see singiong as some kind of obstacle course, in which a feat of memory is important.

What matters is what helps you sing the song the best way you can sing it. It shouldn't be about trying to impress people that you can remember it. Reciting a page out of the telephone book would be much harder, and a much more impressive feat of memory.

I find that if I sing a song from a word sheet or a book, even if I'm doing it into a microphone on my own to record it, it doesn't come out as well as if I sing it without the words in front of me - provided I remember the words. And if I'm playing a guitar and I have to keep squinting at the words it's even worse.

So if it's a song where I need the words at this particular time (it's too new to have in my mind yet, or it's too long since I last sang it), I want the words as big as possible and easy to see. Trying to give a false impression that you know all the words if you don't is phony and a waste of time. And it doesn't work either, unless maybe you're using braille.

Some of the best traditional singers I've seen always have a songbook, one they made themselves, or which was passed down in the family. Using it is part of their tradition, even when they hardly even glance at it.