Do you Trust Your Opponents?

A K J 9 5
K Q 9 2
A K 8 6
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10 8 6 4 3 2
J 5 10 6 4 3
9 5 4 J 7 3
A 8 7 2 J 6 4 3
Q 7
A 8 7
Q 10 2 Contract: 6 NT
K Q 10 9 5 Opening lead: J of hearts

This one isn't quite so elementary. But almost so. Declarer lets the opening lead ride to his ace, cashes the queen of spades, then to the ace, diamond ace, 6 to the queen, and now the 8 of hearts is pushed through to the 10! Oh, please. Count your winners. You've got 5 spade winners, which declarer has already determined, three hearts, three diamonds for 11. Indeed, one thing I didn't notice until I began writing this up was that declarer had rushed to wipe out all entries to the closed hand (and hence access to a club trick)! At that point, she couldn't have made the hand. She might have tried the queen of clubs, which might have induced a second hand low from LHO, but it's a little amazing how players will so often wipe out their key entries -- first thing.
A little count here will indicate a cold contract dependent only on spades not misbehaving terribly, which had already been determined. Five spades, three, three comes to 11. Just use one entry to lead a club honor and another of 3 to cash the established club honor and claim. Oh, but didn't we get a chance for an overtrick with that lead? Yeah, right.
You first need to find that that lead does mean West has the 10 of hearts. And even if so, you still can't make an overtrick unless diamonds are 3-3. We can see that diamonds are indeed 3-3, but that's a slim chance for trusting the carding of opponents on a cold contract in an IMP event where the overtrick might bring something like .12 to add to your score. Please. Oh, and one other thing. If you must finesse in hearts, how about making it the third round, not the second, okay?
Take the opening lead with the king of hearts, test spades, okay, come to the ace of hearts and lead a heart and bingo! That's one way of finding out a finesse won't work, i.e., learning that it cannot work before you take it. Of course, now you've got to sweat out the ace of clubs. Is it with the now uncovered 10 of hearts? Which is why it's not wise to take the finesse at all!
Just count. Eleven tricks outside of clubs, a minimal chance of an overtrick that won't mean much anyway, a certain contract-fulfilling trick in clubs. Need you more? Please.
Another declarer went down in a different manner: Jack of hearts to the queen and now four diamonds were cashed. Not a good idea in view of the fact that if the suit doesn't break, you may have no chance if the now established diamond for the defense lies with the ace of clubs. But wait a minute: That's four diamonds. Now, if we have five spade winners and four diamond winners and three heart winners, doesn't that add up to 12?
Not here. Declarer continued: heart to the ace, queen of spades, heart to the king, ace, king of spades, heart 9 to the 10. Heart 9 to the 10? It's right there. No finesse, but with the top spade and the long spade showing, this declarer chose to lead a losing heart. East now led to the ace of clubs, and declarer won the last trick with the king of clubs. I dunno. I just don't know.