Actually, there are signs, and adults should know them so they can look out for them. It's very unfortunate the Freeh did not use his very loud megaphone to share this information with the general public. If he had, you and millions of other people would be aware of them now. Louis Freeh didn't do children any favors with his bullshit "cover up" crackpot conspiracy theory.
From the Clemente Report:
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Do you know an adult or older child who exhibits one or more of these red flag behaviors
for child sexual victimization?
Doesn’t seem to understand what’s acceptable when it comes to personal space.
Makes others uncomfortable by ignoring social, emotional or physical boundaries or
limits.
Refuses to let a child set any of his or her own limits regarding boundaries or touch.
Uses teasing or belittling language to keep a child from setting a limit.
Insists on hugging, touching, kissing, tickling, wrestling with or holding a child
whether or not the child wants this physical contact or attention.
Frequently walks in on children/teens in the bathroom.
Turns to a child for emotional or physical comfort by sharing personal or private
information or activities, normally shared with adults.
Has secret interactions with teens or children (e.g., games, sharing drugs, alcohol, or
sexual material) or spends excessive time emailing, text messaging, writing to, or
calling children or youth.
Insists on or manages to frequently spend uninterrupted time alone with a child.
Misses or ignores social cues about others’ personal or sexual limits and boundaries.
Often has a “special” child friend, maybe a different one from year to year.
Spends most of his/her spare time with children and shows little interest in spending
time with someone their own age.
Encourages silence and secrets in children.
Seems “too good to be true,” i.e., frequently baby sits different children for free; takes
children on special outings alone; buys children gifts or gives them money for no
apparent reason.
Allows children or teens to consistently get away with inappropriate behaviors.
Is overly interested in the sexuality of children or teens (e.g., talks repeatedly about
the child’s developing body or interferes with normal teen dating).
Frequently points out sexual images or tells dirty or suggestive jokes with children
present.
Exposes a child to adult sexual interactions or images without apparent concern.
Links sexuality and aggression in language or behavior, e.g., sexualized threats or
insults, like “whore” or “slut.”
Makes fun of children’s body parts, describes children with sexual words like “stud”
or “sexy” or talks about the sexual activities of children or teens.
Masturbates so often that it gets in the way of important day-to-day activities.
Has an interest in sexual fantasies involving children and seems unclear about what’s
appropriate with children.
Looks at child pornography or downloads/views internet pornography and is not
willing to show whether children are involved.
Asks adult partners to dress or act like a child or teen during sexual activity.
Minimizes hurtful or harmful behaviors when confronted; denies harmfulness of
actions or words despite a clear negative impact.