First, my best coin. Not rare, but nice.

Then, this.

I know some of you are thinking, "Does he know it's a slug?"
Yes, I do. But I didn't when I bought it.
I was at the local B&M picking out a handful of foreign coins from the "dusty bucket," when I got the bright idea of getting a few coin in horrible condition to practice/experiment with my conservation skills.
In all fairness, my dealer would never do anything shady, but this thing had been pried out of a clump of road tar and was entirely unidentifiable.
Several hours later, this is what I have to show for my efforts.
On the bright side, I'll bet no one would say, "It's been cleaned."