Children are naturally quite perceptive and more open and honest than adults. The children in the town would treat Pearl the same way they would treat Hester. Most children are taught to tell the truth about any and everything, and not to lie under any circumstances. So if a child is in a situation where he or she has to tell "what happened", it would be the truth, with what has been taught embedded in his or her brain. When the town children were "brutally honest" about Pearl and Hester, they were simply saying what was on their minds, which was more than likely heard from someone else; in this case, adults. Children are not constrained by the limits of acceptable social behavior, given their status, and are free to openly express themselves.
Pearl is referred to as a “demon child” because no one knew who her father was. As children do not really know how to perceive things the children just mimic what their parents do and say behind closed doors. “All the kids ignore her” this shows how the children would just mimic whatever their parents would do to Hester and Pearl because they could not perceive what was going on at the time. Children are presented as more perceptive and more honest than adults, due to the fact that the children are more innocent and have not yet experienced life. An adult expresses his or her feeling in secret, on the other hand, a child says what is on his or her mind, because of the lack of knowledge and experience. (Hawthorne)
Since Pearl was seen as "an imp of evil, emblem and product of sin" the people and children in the town saw her as a symbol of evil and would barely even consider her to be a human. Adults can differentiate between what is right and what is wrong, however, children are incognizant of what is right and what is not. Even if a child does not know the truth they are going to speak their mind and say what they believe is right.(Hawthorne)