I think 2 popints of view here. First of all my phone 4S at present and 5S in about 2 weeks stays in a fairly well enclosed case so the only clean i worry about is the screen prints even with a Zagg Screen protector on it. I take it out of the case one time a month only to just get hidden dust that can still get into the case.
The other point being besides the screen people talking about spit and pants and shirt corners kindafreaks me a bit that you would use this or do this to a phone you are looking to keep pristine, unscratched and clean. What do you suppose clothing and such besides a microfiber cloth which is all I use has or made of....?? Scratchy material that is going to be worse, At least use Micro fiber cloths and the slightest bit of clean water, nothing else. Think about it as it relates to you and not the other weird things others seem to be doing and I am not trying to be or come of critical here.