Brian Holcombe
I think it would take a seasoned hand tool user to know in most cases.

I try not to make it obvious, though sometimes I'm tempted.

In many circumstances where a piece is typically made by machines, it's going to go unnoticed. Most slab tables are the product of a giant belt sander, so not many will recognize them as being a product of handwork unless you intentionally leave tool marks.

I've seen it done successfully and enjoy it when it is done well. I do so occasionally by texturing with spoon bottom planes, gouges or otherwise.