May Dad tells the story of a fire warning light he had in a Meteor jet in the 50s. The FRCs said something along the lines of "Point the aircraft out to sea and eject". That was a scarier proposition than staying in the aircraft which seemed to be flying OK. After landing, the techs told him not to worry... Meteors did that all the time!!!
The decision as to whether to treat the fire as real our not could be coloured by how scary the alternatives are.
In a LPC recently, I saw a candidate decide that an engine fire indication was not real simply because the engine oil temp remained OK!!!!! Continued as if nothing had happened, no TEM at all!