The movie reflects reality. “Potty mouthed teens” are normal. LOTS of teens have sex, and while I don’t know the statistics, I think that a good percentage of American teens are “sexually active”, especially those with a purely secular upbringing. Most adults DON’T maintain healthy marriages. Divorce IS the norm.
Juno shows that even in these dire situations, people can see the good and strive for it. As the film goes on, you should notice that the vulgarity (which is striking at the beginning of the movie for us, but probably not for the population at large) drops out. Juno changes as she learns to love outside of herself (first her child and then her boyfriend).
The things that you are complaining about are things that the movie is addressing head-on, and taking the right stance. Juno sees how prevalent broken marriages are, and this scares her to the point of not believing that ‘true love’ is possible. Her father’s response: it’s hard to believe it by looking around, but it is. Relationships CAN work.
Unlike Bella, Juno manages to reveal the beauty and complexity of people, and the inherent worth of life while RETAINING a realistic perspective. Bella exists completely in la-la land.
As for the pro-life girl at the abortion clinic, I wasn’t offended. I didn’t think she was a stereotype but a person. The movie wasn’t making any jokes at that character’s expense. If anything, that scene portrayed something very Christian: truth and grace can work through anyone. The truth has value in itself, a life of it’s own that exists beyond the person speaking. It’s that “dimwit” who makes the concept of life CONCRETE for Juno. Pretty wonderful stuff.
I found this movie refreshing for the very reason you disliked it: it isn’t a piece of pro-life propaganda (again, see Bella). Instead, it’s actually a work of art that can be classified as ‘pro-life’ because the story is told from a perspective that sees life as beautiful.