Yes, I have done that. But it is a pain, and very ugly.
They can, in fact tell if the signature is "stamped" -- and I have had them rejected.
You can buy little stylus pads that hook up with USB that will be recognized as a "mouse" but allow for more precise drawing, but that's just one more piece of clutter to get lost.
It can't be that hard to recognize a touch screen or stylus -- very simple online drawing programs do it. And they already are halfway there with their "freehand draw" button.
