What Did Dumbledore Know And When Did He Know It?

[Cindy C.]

No: HPFGUIDX 27714

The more I think about Dumbledore's behavior, the stranger it seems.  
He is supposed to be a wise and powerful wizard, right?  But if you 
consider the number of times he is fooled by someone or something, it 
starts to add up.

He was fooled into leaving for London.
He was fooled (perhaps) about Lockhart's abilities.
He was fooled by Crouch's impersonation of Moody.
He was fooled by the Goblet of Fire incident.
He was fooled with the Cup-as-Portkey incident.
He was fooled (sort of) into letting Crouch's soul get sucked out.
He was fooled for years by Mooney, Wormtail, Padfoot and Prongs.

Then there are the times when Dumbledore is just out of the loop.  
Like the existence of the Marauder's Map, the many passages into the 
castle, Sirius letting Pettigrew be secret-keeper.  And the times he 
appears to be a bit careless (leaving the Pensieve out when he knew 
Harry would be in his office).

All of that (coupled by this recent bit about him being vain) is 
making me wonder.  Is he letting all of these things happen for a 
reason, or should he re-think the part about being so trusting?

Cindy (wanting to believe the best about Dumbledore)