this is an area of controversy........ IMO i think you should do what works for you, as for me..... i do punish him when he did "bad"..... i am changing tactics though, i use the pee pad method and right now he is in his "rebellious" stage and is currently peeing and pooping on my fiances clthes, SO.... since it is warmer weather (hehe, warmer weather in cali) i have put the pee pad outside and if he doesnt use it then he is going to STAY outside on the balcony (enclosed) until he gets it right
(jk) but seriously i do yell at him and it does the trick