I flat out cannot make my iPhone 4 lose bars with the death grip. Been all over in a bunch of service areas. BUT... My friend grabs my phone and holds it in what I still think is a very unnatural way and it drops bars. Not enough to be 5% of the issue that people make it out to be but it does slowly drop. About three bars worth over 30 seconds. So... Seems like effects some body types more than others? Sweaty hands? Bigger hands? Different magnetic fields?