Dennis shouted all his lines.
Has anyone else ever noticed that Jay North virtually always shouted his lines in nearly every episode? He toned it down a little bit in the 4th (and final) season but especially in seasons 2 and 3 he shouts nearly everything he says. In several episodes I've seen his dad, Henry tell him to stop shouting and also Mr. (George) Wilson told him not to shout several times. It looked to me like Jay's shouting actually irritated the adult actors sometimes.
I'm not saying Jay couldn't act but he clearly was way overacting. He was way too loud and foreceful nearly all the time (with rare exceptions) and seemed to be trying too hard to please. Also, from season 2 on he almost constantly had a fake, forced smile on his face in nearly every scene. I feel sure that was the director's doing. Probably told Jay to smile all the time. Even Tommy (Billy Booth) did that for awhile, but not all the time. Also, none of the other kid actors shouted their lines like Jay did. Of course they were loud when a scene called for it (like a kid argument) but the other kids spoke in a more natural tone of voice. I get the impression that Jay was trying very hard to please everyone and push his performance to the limit, like a theatrical performer would do.
I've seen Jay in some other old TV shows he guest starred on before he began Dennis, and in those he didn't shout. He spoke in a normal tone of voice. Of course he always had a lot of enthusiasm but that's not what I'm talking about. The other kids on the show had enthusiasm too but rarely shouted.
Anyway, this is the only criticism I have of Jay's acting on DTM. He had a bad tendency to way overact and shout his lines. Apparently that was fine with the directors and producers since it appears no one ever took him aside and explained to him that he didn't need to shout. I feel very sorry for Jay for all of the abuse he went through as a child actor. That had to be extremely stressful on him. Also, for all I know maybe the directors told him to speak loudly. It was not intentional on his part I'm sure. The other actors on the show all said he was a sweet kid.