I drag the edge across my thumb nail , then Ill shave my arm hair , if I allready shaved all that, Ill shave my leg hair , bit if I allready shaved all that , Ill shave my ...aahhh ... nevermind
I seriously do drag it across my nail , the Ill LIGHTLY drag a thumb print over the edge , I find I can get a better idea of how sharp sharp is by how it grabs my finger print
when its scary sharp Ill slice a sheet of newspaper or magazine page to find any rough patches on the edge that might need working on .
if its all good , Ill wipe it with an oiled rag and put it away then ,
if ya dont wipe your prints off the edge , itll rust the edge off and you get a blunt spot on an otherwise seriously shaving sharp edge .
If Im buying a knife or just looking at someone elses , Ill drag it on my nail , if Im sharpening my own looking for improvementon allready sharp ..then the first bit applies .