Rant: I've been using the wrong side of a utility knife blade for years and just found out
I was cutting some cardboard for a recycling bin and my neighbor, a retired contractor, watched me for a second. He pointed and said, 'You know you're using the dull side, right?' I always thought the shiny, beveled edge was the sharp part. Turns out, the actual cutting edge is on the opposite, flatter-looking side of the snap-off blade segment. I've been forcing the dull side through material this whole time. Has anyone else made a basic tool mistake that seems obvious now?