The problem may not be false glideslopes "below" the 3-deg one but of a failed glideslope, period, in which the indication centers and remains centered regardless of actual position.
Psychologically therefore, any and all effort to "maintain the glideslope" (high rate of descent, zero rate of descent, etc) is "rewarded", if the pilot isn't cross-checking the crossing altitudes and the DME as ssr has now twice pointed out. The A320 has a superb ND display which should show the position of everything, like the LOM, the airport and so on.
It is hard to imagine how such data can be ignored or just not seen in favour of following either a lobe or a failed glideslope, but it has happened and will continue to happen unless cross-checks are done. It occurred at Apia, at Irkutsk, and I've seen it, recently, elsewhere.
Astonishing, given detailed map displays and all, but there it is.