Either the Best Call or the Worst Call I've Ever Seen - Opinions?

[Mens Rea]

BM 5-10 (I have $7500ish, opp covers)

Folded to me in the Cutoff with KJ [img]/images/graemlins/heart.gif[/img], raise to $30 - opp who is loose and bad reraises to $100. I call.

Flop is 4 10 A.

I check, he bets $400 (I'm thinking he has KK or QQ at this point). I raise to $1000. He just calls. Odd.

Turn 6.

I bet $1500. Again, he just calls. I am almost certain he has KK.

River A.

I push. He calls. Oops.

I table my second nut no pair. He tables the first nut no pair - KQ. WTF?

First, I understand that I overplayed this hand. I've been doing that a lot lately and don't need anyone to tell me. I've been running really hot lately and as a result, I'm full of myself and start to think I can outplay everyone - hence this kind of play.

Has everyone ever been called down by a hand like this? Doesn't the flop checkraise let him know I have at least a pair?

So, best call or worst call ever - it has to be one of the two, no?