We cannot hide all traces of marital conflict from children. It is impossible, and not seem good idea. A husband and wife who are always sniping at one another are not the only ones who suffer from perpetual friction. Children cannot help being upset and frightened when they see their parents fighting constantly. Parents fighting hurts children. Constant bickering and other abusive acts have intense effect on them. Their safe little world becomes a battleground. Feeling of insecurity sets in.
By watching how their parents interact, children learn that conflict is a part of marriage. What is important is how that conflict is expressed. No one would argue that a child would be frightened by witnessing outright violence between parents. But to observe them constantly badmouthing can also have a damaging effect.
It's better for kids to see their parents have a fight in which each of them is expressing his or her personality. That way a child knows that fighting is sometimes a natural part of relationships, and that things can be resolved. Constant arguing, on the other hand, is "like wallpaper--it's always there!"