Who should we trust?

Today I'm feeling a little weary, and a lot angry at society... I'm giving a lecture on persuasive communication today, and the idea of propaganda really jumped out at me - manipulating people's ideas of common sense, in order to make them believe certain things. And I see it everywhere - we are pushed and pulled and moulded by society - often one person or organisation is behind it - and we are completely blindedsided to any alternative views. This week at uni, there is a protest against rape and gender bias - rape survivors and supporters are gagged and are "silent" for the whole day - this is part of the cause not to remain silent about rape. And I love it, I love the concept and I love the solidarity, but at the same time, I want to run around smacking people for being so manipulated. I only feel this way because, recently, I was told of a friend's 14 year old daughter getting raped in the UK, by a 16 year old boy in their complex. My first reaction was shock, and horror, and I wanted nothing more than that boy's appendages to get gangrene and fall off painfully. How could you take advantage of such innocence?? When the child cried help to a friend, who told her mother, the police were there in a flash - boy arrested, girl taken in for testing and questioning - everything was done immediately and efficiently. Nobody stopped to ask whether it had been consensual, whether anything had been forced... (with full knowledge of under-age sexual encounters being illegal) - everyone automatically assumed that it was rape and that the young girl had nothing to do with it. As it turns out, this girl was fully aware of what was happening, and had consented to heavy petting as well as oral sex - at the age of 14. Do we still get to cry rape? And who is looking after the interests of the young boy? The young girl also has a history of crying wolf in situations - how do we know what really happened?
My point is that we have been manipulated by society to the extent that, when someone cries rape, we automatically believe the girl - it would be "morally wrong" to step back and say that one cannot be declared guilty until proved so, yet there are so many people (and apparently children) that exploit this. We are so worried about 'doing the right thing' and taking rape seriously, that sometimes we forget how these types of instances may affect other parties. Labelled a rapist at 16? How does one move past these falsified incidences?
And how does one, as a parent, or a sibling, or a friend, choose who to believe, knowing full well that your child is prone to serious lying, and when evidence does not always match up. Society explicitly tells us who to believe, but maybe it's time to start believing from the brain, rather than emotions...