What is fallacious about the implied argument?

An implied argument is an argument which leaves us to draw the supposedly obvious conclusion for ourselves.  Where an assumption on which the argument depends is not stated it is not readily available for scrutiny and therefore the fact that it is questionable or false can easily escape our attention.  Similarly where a conclusion remains unstated the questionable connection between it and the reasons given for it remains out of view and may thus escape our critical appraisal.  The problem with implied arguments therefore is that they involve a sort of mental sleight of hand that can fool us.