It runs the gamut. Yesterday I doled out the fury when my boy (3.5) wasn't behaving at Christmas photos. It was pretty horrible.
Today he calmed sat on my lap and watched race videos on You Tube with me.
It's so variable I don't try to define it. I've seen kids that are great and horrible....and they are the SAME KIDS. Just like you and I have our moodswings.
The family in front of us didn't get their 3 year old to take the family photo yesterday...he just ran out of frame crying. I'm sure that will be a special card to send out.
You won't understand until you have one/some of your own. Threads like this are why I keep a tight reign on the kids when out in public. Maybe too tight, since maybe they don't like what you're doing!
At home, it'd be impossible.