Rabbis

Question

I am not sure I understand your response to Emily in which you said that if your rabbi is qualified you should follow his opinions. I agree with that when it comes to halakhah, but even if your rabbi is a great talmid hakham, if he says something totally incorrect, you don't have to follow him (see beginning of Horayot). For example, if your rabb said that you can't eat a product without a hashgacha it doesn't make it correct and you don't have to follow him. Do you disagree with this?