Televised political debates might not have much effect on the voting public, but their impact on those who comment on TV debates is fascinating.

Grisly and predictable, but fascinating.

What did we learn after the first Salmond and Darling contest? That the Guardian/ICM "just a bit of fun" snap poll had no resemblance to what proper surveys call reality. In three of those, the Yes vote went up. The alleged drubbing that left the First Minister bruised, bloodied, on the ropes - fill in the rest - in that "crucial contest" did not produce the proclaimed result. Quite the reverse.

Yet what did we hear, endlessly, before Monday's fight night? Now it was "make-or-break" for Mr Salmond. He was in desperate need of a comeback, of - that word waiting to be banned - a "game-changer". Never mind those polls: once again, everything was hanging on a weird symbolic contest conjured for TV. The inconvenient facts of public opinion were simply ignored.

On Monday, the First Minister delivered: by now, that much should go without saying. The ICM scorecard was unambiguous: 71 per cent to 29 per cent of a group of 505 decided the triumph in this bit of politics-by-proxy went to Mr Salmond. But had it altered voting intentions? A thoroughly unrepresentative sample, one whose views turned out to be irrelevant after the first contest, said that it had not.

Funnily enough, most professional witnesses to the latest TV show also managed to decide the humbling of Mr Darling had not changed anything. When the First Minister was judged to have lost, things were said to be grim for the Yes campaign. When the Better Together chairman took his hiding it was, instantly, "too early to say" whether a floundering, evasive performance mattered.

Double standards are nothing new in this campaign. Strange twists of logic have become commonplace. In other circumstances, both sides have been keen to say "it's not about personalities". Turn on the television cameras, roll out the sports metaphors and wheel in that carefully-selected audience: suddenly all that matters is one man in a suit against another.

Has the Yes campaign said endlessly that this referendum is not about Mr Salmond? It happens to be true, a fundamental fact, but that was ignored on Monday night. Talking about "him" has been the tactic of Mr Darling and his Unionist friends for months. As two over-rehearsed politicians went at it, independence campaigners cheered their man regardless.

Have the Labour folk in Better Together been desperate, meanwhile, to avoid the charge that the former Chancellor is just a human shield for a Tory-led Coalition? More than desperate. It would be very wrong, they reckon, to "personalise" their cause. On Monday, nevertheless, they bet the house - Labour, Tories, LibDems and various strange bedfellows - on one man.

He lost. But if the poll findings after the first debate are the reliable guide, it should not matter. If anything, we should be ridding ourselves of a taste for gaudy spectacle and asking if these TV debates have any point at all. They don't fit the facts. Why bother with them unless we are determined to satisfy political hacks who have watched the West Wing too often?

The first proper polls will be interesting, then. If No has been damaged by Mr Darling's performance it will tell us something about the nature of the two campaigns, given that Yes prospered after Mr Salmond's setback. Either these television debates are worse than useless, or one side in this contest is more resilient, more deeply-rooted and better connected to the public mind than the other. We will see.

My partisan belief is that Better Together can guess the truth. That fabled campaign software is probably delivering its doleful tidings even now. This is less because television debates win hearts and minds than because too many Unionist hearts were not in it, so it seems, to begin with.

Monday's debate was Mr Darling's last chance to articulate the positive case for Union that he has been promising for months and years. He didn't even bother to try. The things that could be said for and about Britain, the things David Cameron has now and then attempted to state, formed no part of the charge of the lightweight brigade into the valley of prime-time death. There was not a word. Even for this Yes voter, it was faintly shocking.

Three hundred and seven years of Union. An "irrevocable" (as Mr Darling has it) vote almost upon us. Three centuries of amity, argument and allegedly common endeavour. All that culture, all those bonds, all those presiding spirits of the Labour Party hovering beyond the lights. Surely there would be something? All the former Chancellor had to hand was another querulous attack on the relative merits of currency arrangements. The audience groaned.

What became of solidarity? What became of the universal rights of working people? Mr Darling instead turned out to be ill-briefed on child poverty, evasive on Labour's embrace of welfare spending caps, obdurate in his refusal to condemn the futility of Trident, and a poor gambler with currency, his own chosen sport. Which currency plan - A, B or beyond - would he recommend for a country recovering its independence? Mr Darling is another of those proud Scots who is too proud to say.

In terms of the campaign, the tactic of "going" with the currency issue yet again was the most fascinating item of the evening. After the first debate those legitimate polls had shown the tactic to be, at best, ineffective. On Monday, even the No-supporting part of the Glasgow audience seemed less than enthused by Mr Darling's return to the attack. This time, Mr Salmond was ready with a menu of choices that have worked well enough around the world. Still the former Chancellor ploughed on.

It made sense only if you are wedded to the playbook from the last Quebec referendum. This holds that fear works in the end. Keep nagging away at any hint of unease, it suggests, and you will herd the sheep back to the paddock in the last weeks of the contest. The Better Together case might sound technical. It might sound abstruse. All that matters is the ominous hint of impending doom. Then you call that "the positive case".

We were supposed to believe, meanwhile, that the NHS is safe because health is devolved entirely to Holyrood. The same cannot be said of all budgets. The Westminster parties each surrendered to privatisation years ago. Have their Scottish branch offices now renounced that ideology? Does Mr Darling find it as despicable as shadow health minister Andy Burnham, the man with a whole privatised hospital to his name who now, too late, warns England against the great sell-off?

It might not matter in the polls or in the vote. Perhaps the First Minister's unfortunate habit of emerging from behind his lectern like a timeshare salesman will prove another of those "blows to Salmond" on September 18. Somehow, I doubt it. Better Together is a Potemkin village of a campaign. The only important things to stand revealed in Monday night's entertainment were the deep cracks in the facade.