No offense to the Quinn fans but she has ALWAYS been shallow and popularity seeking, even at the height of her pregnancy. She learned to be nicer to people and with the exception of Rachel and Puck, still is but still she only cares about popularity. We presume that after Beth was born, something happened between her and Puck yet they were separated by Audition. She held out the possibility to him until he was arrested and she met Sam. Sam was about popularity, he was the new QB, he was the golden boy and he was nice to her. In Duets she only wanted to stay on top, in Audition she cared about getting back on the cheer leading squad. Any mention of the baby (whose name she has NEVER said btw) relates HER body, her perfect figure etc. There hasn't been any sudden departure from character development in the last 3 or 4 episodes, she's behaving exactly as she always has. The only difference is now she taking up screen time with it.
I don't even know how Quinn has fans. Anyway, the Glee formula for any character always seems like it's one step forward and ten steps back.