Minnesota Public Radio has a great photoessay/poll giving particular actual examples of the kind of issues faced by election judges when it comes to determining ballot results on hand recount.
Here's an example, called "The Arrow":
Who gets the vote? Franken, Coleman, or nobody/indeterminable?
Of course, in the real world, one's decision would be governed by this Minnesota state statute as a guide to determine voter intent. While it is helpful, it is, in many ways, not helpful enough.
Here's another, called "The Confusion":
MPR informs us:
The Coleman campaign kept this ballot from going into the 'Other' pile. They argued that while the voter filled in the bubble next to Dean Barkley, the voter had intended to vote for Coleman because of the small dot inside Coleman's bubble.
Hmmm. I don't know about that.
Anyway, I don't envy these election judges.