I'm not suggesting that anyone do this but I usually use the tip of my finger. If you run it against the blade very lightly and you feel an ever so slight resistance you know it's sharp, if it feels smooth it's dull. I also use this method with planes, and check them as I lift them from a piece I'm working on each time out of habit. One day I got an electric planer and did the same thing while it was still spinning and took the end of my finger off. Be warned
I tend to know how sharp it is by how it catches on my skin and slid e a bit of paper very slowly
Or a VAMPIRE !!!!
I've never liked razor sharp knives it's just overkill really. I much prefer a reasonably sharp knife that can be honed quickly and easily to do the job required.
The most dangerous knife is a blunt one! unfortunately this statement was witnessed by me in the mid to late 70's a guy i used to work with Richard,..........I can't remember his surname was working in Williams brother Butchers with me and using a blunt knife was boning out a pigs head, he had to put more pressure in the cut than he should have as the knife was slightly too blunt and it came out of the pigs head and cut through his femoral artery and he was dead before the ambulance got there
So personally i like them as sharp as i can get them!