Food coloring dyes can be a real nightmare
As a gross oversimplification there are dyes that are set by heat, and there are dyes that are set by Acidity of the dye mix and there are fabrics that will accept dyes and some that are pretty dye resistatant
Nylon cotton wool and silk are easy to dye or stain, Polyester is very hard to dye or stain. A lot of clothes that for instance a organization that might be subject to fire must be made out of cotton, the polyester fabrics melt and cause severe skin damage
So food coloring in Karo syrup and all its varieties looks great. I have never tried the CoffieMate it might be worth a try I would guess it changes the PH but I would be concerned with natural fiber clothes getting stained.
Years ago I did a magic show with a now well known artist, it involved sawing to remove a person body parts with a table saw, we did use actual meat bone and blood. It worked great but was a terrible mess, and today I am sure would be a health regulation nightmare, In fact now that I think back at the show, it was so gross and realistic that a lot of the mess was from the audience throwing up
Sharyn