There's a difference between a knife drenched in blood and a tiny bit of blood from a cut, certainly, but as far as forensics goes that may not matter - they may want to find any evidence of blood, like some blood caught in the space between the handle and the blade, on the assumption that a killer may have tried to clean blood off a weapon.
Surely cleaning blood off the knife makes just as much sense if it was a cooking accident as if you've killed someone with it?
That's a strong claim.
I'm not a professional chef but I like to use a chef's knife, and I cut rather fast. Yet I don't remember ever cutting myself to the point of bleeding. I only remember scraping off nails and skin.
> like some blood caught in the space between the handle and the blade
I reckon that if it gets stuck between the handle and the blade then we're talking about more than a little blood.
I rarely cook, but I work on cars a lot. Cutting my hands and fingers is part of the routine. Oddly, such cuts have never gotten infected, even when the dirt gets embedded below the skin. I think car grease is an effective bacteriacide!
(I find wearing gloves while working on a car uncomfortable, though I'll do it when cracking a rusted nut loose - when it finally gives way you'll always bang your hand against something.)