Communication isn't always straightforward. About the only thing that a parent can be sure of is if their child complains of feeling ill, this being evidenced by fever or another serious symptom. Otherwise, a child's complaint may be valid or indirect, which is similar to the behavior of adults.
Consider the man who is asked to purchase something by his wife and "forgets." This may be accurate if he has pressing issues on his mind or indicate his indirect expression of anger by behaving passive-aggressively. Similarly, a youth may behave in a puzzling way or make a puzzling statement to express a concern about the parent or another which they fear to express openly. Perhaps wanting greater independence than the parent allows or to react against what they interpret as the parent's deprecating comment.
As I never tire of repeating, the unconscious is very powerful and one must respect its power.