All apps I have tried seemed to "know" when a fast charger was unavailable (being used by someone else), although I never checked those out. None of the apps I have tried "knew" when a the particular charger I was going to visit was not working.
I have made so far 4 attempts to fast-charge.
#1 . Dead, but resurrected by a remote over the phone
#2 . Same outlet as above, on a different occasion - working normally
#3 . Zombie, with the screen giving the following number to call: (000) 000-0000 to call, literally. Zero you-know-what's given.
#4 . Dead and gone - no company name, no number to call
Conclusion: Would be great to have n app that can monitor the charging stations' functionality in real time, as they do the availability.