There are 2 false G/S's. One at 1 1/2 degs and 6 degs.
I don't know about these days, but certainly during my time on flight navigation aid calibration in the 1970's we checked for false glide slopes as part of the commissioning process and scheduled flight checks. There were false glide slopes which were about 60 degrees, and noticed by flying in level flight along the localiser until past the glide slope transmitter. Of course these were un-flyable unless you were a Stuka dive-bomber - but they did exist.