Three failure modes: turning renunciation into a self-help mantra; renouncing without being in a state of grace; treating renunciation as exorcism (it isn't). Each undermines the practice.

Misuse 1: Self-help mantra. Reciting the prayer as a calming ritual divorced from the will-act it embodies. The words have no magic; the act of will is what renounces.

Misuse 2: Renouncing without state of grace. The renunciation prayer is not exorcism; it is a baptised Christian's exercise of the authority that flows from union with Christ. If you are in habitual mortal sin, deal with that first (A6 Confession; the sacrament restores the relationship on which renunciation rests).

Misuse 3: Treating it as exorcism. Renunciation operates against ordinary spiritual influence — temptation, suggestion, harassment. It is not the rite of exorcism, which is reserved to specifically delegated priests under specific conditions and never to be attempted by lay people. If your situation looks beyond ordinary discernment, see a priest. See SWADOS 1's distinction between ordinary discernment and extraordinary exorcism.