Monsters do not Bleed

Notes:

I would normally spoilers since this is the ending of the Genocide run, but KYM for this tells me not to.

That being said I saw this and was very surprised, Every monster you fight turns to dust, any cut marks are just opened wounds with no blood. But Sans shows blood and you never actually see him die.

Is sans Human? Is it just ketchup? is he a experiment from his father? tell me what you think.