Yes, this is true. If they avoid being at home, keep your eyes open. If they actually tell you of instances or situations they have been in with an adult where they were struck or intimidated in an unethical manner, log it. An important sign that a child has been victimized to a higher degree is when they justify the reasons they were treated in such a manner. For instance, if they explain that they deserved the treatment they were given, log it and keep your eyes open.
Children have no reasons to justify being hit or smacked around.
Abusers will strike first, apologize, then justify. I'll try not to do it again. Basically turning the entire situation onto the victim, once again, while under the guise that they are actually apologizing. Kids want to believe that no adult would hurt them on purpose, especially not a parent, so any type of apology given in just about any type of sympathetic manner is going to appear highly attractive compared to the abusive situation they had been victimized in. In essence, they'll buy it for survivals sake, and any attempt to prove the apology was fake will destroy a good part of what these kids learn to survive by.