NZ 60 technically wasn’t a false GS; it was a ground failure which radiated a test signal but without identification of the error condition. The industry has taken action to prevent this.
False glideslopes occur at alternate multiples of the main beam, e.g. 6 and 15. AFAIR these are not null signals but indicate reversed sense and may not be flagged as ‘off’ or unusable.
There should always be check of altitude against range during an approach – altitude as the first priority as it is the killer parameter.