8. Plot Abandonment
A favourite of television writers everywhere Glee is notoriously bad for dropping storylines (particularly regarding secondary characters) and admittedly has been from the outset. The start of Season two saw cheerleader Quinn apparently forget she had recently given birth and the cruelty that she witnessed whilst pregnant so to return to her life exactly as it was with no sense of humility or obvious character development at all. This plot was briefly revived much later in Season three when Quinn appeared to suffer an emotional break down before declaring herself happy and healthy only a few episodes later. Speaking of which, the adoptive mother of Quinns baby Shelby simply disappeared off the face of the Earth never to be spoken of again when this plot was wrapped up. A similar fate (and probably more damaging flaw in storytelling) met gay teen suicide survivor Dave Karofsky later on in the season.