I don't think that a player on 2nd base letting the batter know were the catcher is setup at is cheating. Is it needed? Not really, the player on 2nd is part of the game.
There has been major investigations in recent years of professional baseball & football teams for stealing signs
WHY- because it is not only unethical also considered cheating it is illegal in the pro's. Coaches have recently been been fine fined $500,000.00
Now just because its illegal in the pro's "I'm sure" it doesn't make it illegal in High school & travel sports & just because a parent or some other spectator is doing the sign stealing instead of a coach doesn't make it o.k. When Bill Belicheck was fined for his team stealing defensive signs from the NY Jets he personally wasn't the person performing the cheating action but was the coach responsible for knowingly allowing the action to take place. Just like many coaches in Youth/HS sports do.
I believe that spectators should watch games & cheer their team on, not try & be an influence on the outcome of any game by calling pitches & telling the batter were the catcher is set up at ect...... I thought one of the lesson's that Youth/HS sports was supposed to teach our youth was right from wrong. HS sports are an extension of the classroom, cheating is not allowed in the classroom. Mommies & daddies aren't allowed to help ther kids cheat on test's but yet some consider it o.k. on the ball field??
Good teams beat other team's on the field.