Essentially, there were/are two methods to display "blood spatter" on a character. The first was a transparent overlay but instead of using this technique, I replaced that method with the second, a total skin replacement method. The following are examples that were to be included in the patch.
This would be the new snow cammo sleeve with such an effect. Of course this is only one level of "pain", increasing in "gore" as the body part is affected. Powder burns, blood caking and skin penetrations are intensified as the damage increases. A circular dark red stain is far more life-like than even the "graffiti brush" effect seen here. This is a first revision.
Likewise, this was the head model. Added various dirt stains, abrasions tissue edema (swelling) and bruising.
Quite honestly, as it turned out, much of the damage skins I worked on were more realistic as subtle damage to gear versus wanton carnage. Bullets (unless high velocity) will not penetrate most body armor so this would not show damage except for material tears. We assume that the reason our heroes in the game survive from multiple incoming ballistics is armor, ergo most bullets strike these sufaces and don't actually rend flesh. Any wounds that lead to massive blood-letting would not be conducive to a player that still ambulates and is able to fight. Therefore, if a body is to be smeared in pools of blood, it would make sense to add this to the corpse skin, not the walking-wounded models.