I reckon a few on here are confusing using song sheets with other issues.

The famous and infamous mentioned above will employ a combination of practice and sheer talent, on the basis that memory skill is not as high on their priority list as ensuring the performance sounds good.

I think the singaround beef expressed by many is based on, forgive me if I miss anything;

If you don't try to learn the song, your concentration on the prop lowers the standard of delivery.

A shorter repertoire of well rehearsed songs beats a "repertoire" limited only by how many pieces of paper you can cram into a file.

I will hazard a guess that every one of us who has had a pop at crib sheets has suffered from trying to entertain a room and seeing people flicking through to see what they are going to mumble next. Most ignorant.

Yes, I do stick a piece of paper with first few words of verses of songs I am unsure about to my guitar. Don't confuse crib with not knowing in the first place.