Sheer Foolishness

A 2
K J 8 7 5 4
J 10 5
9 7
Q 5 K 4 3
A Q 10 6 3 2
A 9 4 3 2 K Q 8 6
Q 5 4 2 10
J 10 9 8 7 6
------
7
A K J 8 6 3 Opening Lead: A of diamonds

South
EastWestNorth
Pass 1 2 2
3 4 Pass 4
Pass 5 Pass 5
All pass
This is another way of violating simple common sense on a preference bid. And this was compounded by misplaying the hand, so with a level unnecessarily one level too high and then misplaying by a trick, declarer was down two.
South had bid his two 6-carders, and North had clearly expressed his preference, which should've been honored for about three reasons, to wit: first because it was North's freely expressed preference, secondly because it's a major, which you'll wanna play in over a minor if the major appears adequate, and lastly because the return to clubs pumps up the level of bidding one notch for no good reason. Yes, North only expressed a "mere" preference, so there perhaps isn't any robust fit here, but how do you rectify that by continuing the bidding?
Yes, I considered the possibility that South wasn't violating preference so much as looking for slam. After all, he (probably) has only one loser outside of the spade suit, and if there's a good fit . . . It seems wrongheaded in a Jaci-high suit where partner has expressed only preference, but who knows?
Now, to the play of the hand. West gets off to two diamond leads, declarer ruffing the third and starts a double finesse in spades. (Some declarers weren't taking that double hook, but it works if West has a doubleton honor, or both outstanding honors, and this declarer got that much right.)
East came back with another diamond, declarer ruffing and now when he draws West's Q, he has how many trump left? Yes, the answer is only two. That's two ruffs of diamond leads and two rounds of trump. But before drawing the Q, declarer took a detour and cashed his ace of clubs! Why on earth did he do that? The ace of spades is bare in dummy, so there's no percentage in leading toward it, and if I've said it once, I've said it a hundred times: Don't cash your top winners without good reason!
With that A of clubs, declarer could have drawn the Q of spades, come to the closed hand with that ace, draw East's last trump, and now looking for a 3-2 club split (with one trump left), he bangs down the A K of clubs. He doesn't get that 3-2 split, of course, but he gets something just as good, which is the 10 of clubs, allowing (the careful) declarer to knock out the Q, ruff a diamond lead and claim.
But declarer didn't have that ace of clubs, and now leading a second round of clubs from dummy, East ruffs for down 2. The ruff was the defense's third trick, and declarer still had to lose a club. Sloppy bidding and sloppy declarer play. The result being just what South asked for.
I didn't realize when I typed the above that I had two more declarers who managed to go down. One got faked out by a low spade lead from West at trick two. Up went the ace, and declarer had to lose two spades in addition to a diamond and a club.
But the third declarer takes the cake He got a low club lead! That should've helped him, for now declarer can afford to lead a second round of clubs from dummy when East has another trump. If East ruffs, declarer plays low and now with two club leads gone, he doesn't have to lose any clubs. But here's the corker:
A low club, East playing the 10, declarer goes up with the K! He went up with the K instead of taking the trick with the J! Now he played his spades correctly, finessing the J into the K, taking a spade back and now a club lead from dummy was ruffed by East, and that should've been the end of the hand, except for the diamond the defense has coming. But of course it wasn't. The defense got two spade winners, one diamond, and since declarer had played the K at trick one, he still had to lose a club! Oh, me.