What can I do about my 14 year old daughter being too easily trusting of other people? Could this have to do with the fact that she's already socially vulnerable (to be specific, bullied)? She is diagnosed with ADD too.
I have to disagree with the answers I have read, I do think ADD correlates with this issue. The reason is self confidence and doubt. When you have ADD, you have experienced a lifetime of being smacked upside the head with deadlines you missed and assignments you forgot. That takes a huge toll on your self confidence.
Thus, when you meet a person who is a user, when you get that gut feeling that it isn't right, you ignore it- because your gut isn't reliable. Your gut didn't give you any warning about the final exam you forgot to study for, or the thousands of lunches you've left at home in the fridge. Your gut isn't trustworthy to alert you of a potential issue. So you ignore your gut and try to rationalize the behavior.
ADD makes you VERY good at rationalizing other people's nonsense. The reason is, ADD makes it easy for you to be very creative, and you can easily think of all kinds of legitimate reasons (albeit far fetched ones) that could explain the behavior.
Ask a person with ADD how many things they can think of that you can use a brick for. They will give you at least 30 uses. Ask someone without ADD and you're lucky to get 5. That seeming lack of creativity though, is in fact the work of a strong filter which ADD people completely lack. That's the filter that says, don't think about 100 things you could do with a parking ticket (wallpaper your bathroom, make a kite, use it for scrap paper, wrap your lunch sandwich in it, use it to write a love note etc, etc) the filter says PAY the TICKET and MOVE ON!
That same filter will tell other people: This person's story doesn't add up I may be experiencing a liar I will not trust them. Your daughters brain says, well, maybe they WERE captured by wild ponies while camping in the Everglades. Anyone can go to the Everglades and they very well might have wild ponies and wouldn't it be amazing if animals had thoughts like humans etc etc. She doesn't focus and filter enough to sniff out their Bullshit bottom line.
You need to talk to her about this. Not one conversation, but an ongoing theme. When you see a blatant liar on the news- talk about it. Anytime you see a deception headed your way- discuss it. Talk about how you focused and filtered what was most important to your decision making and how you trusted your knowledge of these things. Help her to build confidence in her ability to spot truth from deception. ADD doesn't mean she cannot learn it, it means she will learn it differently. It will take longer. Her confidence in her own gut instinct will need to be addressed, mostly as she gets better at spotting deception she will build that confidence, with your encouragement. She will not be the kind of kid who spots bullshit innately, but she can learn it well and keep the lessons with her all of her life.