A set of (edible) blood albedos used in this short Halloween film. Drops, smudges and splatter all over the place.
Apply by mixing them (multiply) with existing diffuse maps, and adding some (parallax) bump and reflection by inverting the maps and fiddling with the contrast. (Or as projection maps, which was quite tricky in FStorm at least.)
As I don't think you will use these textures in your everyday interior renders, it might have to be shelved until future Halloweens.
Various sizes, PNG 8-bit: