One thing that I have always hated in Second Life is the insistence on the part of some clothing designers that one should really alter one's body shape in order to fit their fantastic items. Well, they do not mandate this - one always has the choice not to buy clothes, after all. There is always the option of wearing a plywood box instead.
I seem to have managed in general, but I was interested to see how the advent of Mesh might affect this - reading Vaki's post here, linked to from New World Notes, I suspected that it might not be purely positively. On a quick examination, I believe that I was correct, and that mesh clothing items are less flexible and modifiable to one's personal shape than those based on even prims and/or sculpts.
Here, for instance, is a tie. It is a nice tie, but clearly floats a little way above my chest, and this is fairly obvious in person. "Oh well," was my immediate reaction, "I will just resize it a little". Well, one can't do that. "Oh. Well, in that case, I will move it down a little on my body." One can't do that either. "Oh. Well, I will take it off then."
It seems to be extremely difficult to right-click and edit such mesh attachments in the first place, which I suppose is reasonable given that one appears not to be able to do anything with them anyway.
And this is just a small item. What happens when the item concerned is a shirt or trousers? I can answer that - the mesh is inflexible, and either one seems padded with cotton wool or one sticks out through the surfaces. This is not clothing, this is some sort of fibreglass costume.
Maybe there should be some sort of shape registry, which holds a series of approved co-ordinates that mesh clothing manufacturers can use, to make things for, say, "size 10", or "size 16", which don't fit. That works very well outside of SL after all.
By the way, I have just noticed the gap between my hair and the hat. The key point is that I can move the hat.