We need to not judge at the outset that when one repents that it isn't genuine. We need to repent once, no matter what we've done. Repentance is not saying "Sorry." Repentance means turning away from sin and walking the opposite way---in righteousness.Do you ever trust a mortal sinner who only says 'sorry'. Do we trust our repentance if after a mortal sin all we say is ''oops sorry Lord''?
It doesn't matter whether we rust ther epentant sinner. God will take that repentance and do something with that life.