This is really unfair comparison to Optimum Power Clean. I have photography evidence that all I used was water and canteen soap (those real cheap soap that you sometime even think twice to touch because it is just slimy but no cleaning property) and my finger was clean 99% clean except a small line under my finger nails which I refused to put extra effort just to make my point that morning to SPR. Unless you used a magnifing glass under my nails, you cannot defirentiate indelible ink VS my just having dirty finger nails.
So if I had a toothbrush and OPC, I am very sure the aliens would make my finger spotless clean.
ps. this is not meant to be my rant on indelible ink... Just my testimony and faith OPC will clean your fingers much better than that.. hahaha :P