Originally Posted by Ohm

It's probably because you're concentrating too much on not spilling the coffee. When I was a waiter they used to tell me to not look at the coffee when I was taking it out to the table and it worked. If I looked at it and thought about what I was doing then I more than likely spilled it.

The same could be said with water. You're not concerned about spilling water because it doesn't stain and will dry relatively quick. Also, the temperature factor plays a part. No one likes hot coffee spilled on them.

Try it and see if I'm right.