Since the complaints about suspects' eye damage in the mid-Sixties, all formulas have been weakened across the board. The Mace-type sprays have proven to be much less effective than once believed. Many people can take several streams of the stuff square in the face with no immediate ill effects. It only works right off when it's sprayed in the eyes, which is a no-no. Even that won't work if your assailant wears glasses, or shades.
Drunks are almost immune.
The instructions say to spray at the chest, so he'll inhale the rising fumes. It just doesn't work that way. Curb 60, the most potent such spray. On one occassion, I was accidentally sprayed in the face with it. I had sense enough not to inhale, but wiped off as much as I could and held my breath as I walked to the nearest sink to flush the exposed skin.