I think the proof AFCIs work and the proof they are garbage is the same. In my limited experience, they trip when a light bulb burns out, when a light switch sparks, when a clothes iron cycles, when a heater thermostat switches and when a vacuum is used. I saw an extension cord run into a bedroom to overcome the problems with the AFCI breaker.
The standard excuse for being late for work should be "My AFCI tripped and my alarm didn't go off."
