I think one way that wasn't brought, and is more probable that potential criminal organizations rivaling to hire Sarah, is the good old psycological trauma. And, it makes for really dark settings.
First of all, a mind reader has probably a high empathy level. While she can read someone's mind, she can also read their emotions. And she can feel their emotions while she says to them she can read there mind. Do you feel scared at a mind reader? She feels it, and knows she is the cause of it. How can she not be depressed?
Maybe she tried saying it to someone in the past. It is probable that she only disclosed this precious information with someone she was close to, and was really trusting. Probably a long time relationship. And it got ugly, quick. She could feel their sudden horror, and she could read their train of thought, the implacable doom of ending this beloved relationship, and feeling their disgust toward her, as if it was her own disgust.
Not only does she have a pretty serious trauma from that experience, but she is often reminded of it when people are surprised or doubtful of her slips.
Hiding from trauma is a really often used strategy.
From your wording, I get the impression that Sarah always had that ability, since she was born. And that can lead to more traumatic and dreadful experiences.
Where did she grew up? Was it a loving and positive family, that was fully comprehensive of her unique ability? Or (more probably in this case) an autoritarian, or violent family?
If she was constantly grounded or beaten by her parents from pretended eavesdropping and lying about it, she has some good psychological reason not to talk about her ability to people.
And of course, growing up reading other people's mind can be itself traumatic. Not only is today's "boring" world quite traumatic to girls. But Sarah in that case not only got to hear or see some traumatic sexual experiences, she could read the adult's mind. And a 10 years old is not prepared to some of the nasty stuff going on in some minds.