Hey guys,
I recently has the same loud buzzing with my iPhone 4S. I setup an appointment at the genious bar and when I got there the guy looked at me like I was crazy. I love apple but he did not seem to care. i told him some of the demos did not make that noise( i tested prior to my appointment). He told me that some of the different models for ATT or SPRINT are made a little differently and mine which is Verizon just makes that noise because of extra space and that the motor in the new 4S is EXTREMELY powerful. lol. He even told me his did it, and let me hear the buzzing from his.
My response was simple, "Well I guess yours is broken too." I insisted that he replace it since I have only had it a couple days and he did but warned me that it would make the same exact noise. I said,"If it does ill stop crying and leave". haha. So a little time passes he comes out with a new replacement and we activate it. I have him call it from there, and what do you know... This 4S doesnt make that loud annoying vibration at all. I said thank you, he noded then I told him that he should call Applecare and get that loud buzz on his phone checked out.
Moral of the story guys is this, Whatever they say is because they are jsut trained to do a certain job a certain way. No offense to them, he was just doing his job and didn't look into it further than that. But because of this specific thread and all of you having the same issue I decided to be persistent. So whatever they say, just insist they replace it. You will more thank likely get a quiet vibrating one like the one I have now. I hope this story helps some of you.
-Dom