There have been plenty of times that we have taken our OC spray out and and just started shaking it prior to attempting to arrest a resisting suspect. If they've ever been sprayed before they know what's about to happen next and in most cases that's enough to get them to comply. The same thing goes when you unholster a Taser and put the red dot right on their chest. Sometimes that's enough to get their attention and compliance.however using pepper spray works best when your opponent isn't expecting it.
Even though the scenario being discussed here concerns potential victims that are not in uniform, the situations are similar regarding how a suspect decides whether or not to fight an officer. Now if they are drunk or drugged up - that's an entirely different story.