This is true.
In the 1980's in our hall we had a new ventilation system put in. It was just as crap as the old one but I digress.
The old system had a dial thermostat on the wall which was disconnected but left in place until the next wallpaper hanging.
An elder got on stage and said "if anyone feels it is too hot or too cold then speak to one of the attendants and he will help".
I was an attendant and we were told that if anyone wanted the heating changed up or down we should go to the thermostat and move it in the appropriate direction.
Of course nothing happened because it was disconnected! But the person believed something was being done! This lasted for about a year until the hall was remodelled and the redundant but visable thermostat was removed.
Placebo at its finest!