I'm not sure if it would work or not, simply because I've never tried it, but the theory makes sense. We carry at the fabric store I work at Tulip brand fabric paint. It comes in a handful of different finishes including a shiny, and most basic colors. Theoretically, if you thinned it down and used an old paintbrush, you could throw the appropriate blood splatter at your garment.
If you go this route, you won't need very much paint at all (remember, it's being thinned out so it flows a little better), so you shouldn't be spending more than $5. I just don't know if the finish will stay once thinned.
I hope that helped a little bit.