That £500 question just won't go away.

It's in danger of defining the referendum campaign. The latest Scottish Social Attitudes survey confirms that a majority of Scots would vote Yes if they were guaranteed to be £500 better off, while only 15% would support independence if they were £500 worse off. The survey of 1500 voters was conducted in October, before the White Paper on independence. Are Scots really so crass they would trade their country's freedom for the price of a mini-break?

No, I don't think that is the right interpretation. This is less a considered verdict on the virtues of self-government and more of a plague on both your houses by an alienated electorate; it's a collective thumbing of the nose at the political classes and their vanities. Voters say: stuff your phoney disputes about whether to keep the pound, the euro or the bawbee, and how long it would take to rejoin, remain within or lurk outside the EU. What really matters is that people are still hurting from the longest running recession since the 1930s.

Voters told the Social Attitudes Surveyors, not for the first time, that they feel let down by both sides in the debate, and that they are just not getting the information they feel they need to make a considered choice. Or, to put it in the vernacular: the politicians are talking mince. They have a point. Step back for a moment and consider how this campaign has come across to voters thus far.

The Yes campaign, wary of frightening Scots with the prospect of separatism, has increasingly resorted to Unionist language and imagery while the No campaign offers a lurid Hammer Horror version of independence that is an affront to the intelligence.

The concept of independence itself has become so muddy and malleable that no-one really knows what it means any more. According to the SNP, independence involves a "new UK" in which many of the existing economic and constitutional arrangements remain intact: Queen, pound, Bank of England, Nato, pensions, defence, NHS, BBC, energy market, the National Lottery. The list grows longer by the week.

But, according to the No campaign, independence means border posts erected to keep Scottish immigrants out of England; Scots being told they can't use the pound (nyah nyah); and Scotland being thrown out of the EU and left defenceless. This is puerile. People are rightly annoyed at the quality of argument.

The economic debate is a dismal stalemate. The Scottish Government says that Scots will be at least £600 a year better off as a result of independence. The UK Treasury and London think tanks such as the Institute for Fiscal Studies say Scots will be £1000 worse off. The reality is that no-one knows. The Yes Campaign claims the Scottish economy can somehow be galvanised by 3p off corporation tax and access to oil revenues; the No campaign asserts that interest rates will rise with independence and that the oil is running out.

And the fellow travellers in the constitutional journey are also on dodgy ground. The Right tells us that Britain is one great family in which we are all in it together (and who do the Scots think they are saying otherwise?) On the Left, there is a new form of constitutional opportunism. The Radical Independence Conference proclaims the virtues of the Common Weal, while its leading lights, including the former Labour MP Dennis Canavan, say they don't actually believe in independence; they just can't see any other way of getting socialism in one country.

The media share the blame for voter disengagement. The press relentlessly recycles the same non-stories about Europe and the pound, leaving readers in a state of irritated boredom. Then endless studio debates are broadcast featuring the same politicians arguing over the same disingenuous agenda.

What the political classes can't admit is that the referendum is really a historical accident. The SNP weren't supposed to win an absolute majority in the Scottish Parliament in 2011, so no-one thought we would be having a referendum on independence, at least not now. Scots voted for the SNP by a landslide, not because they wanted independence but because they were sick of Labour and wanted better devolution.

Which, remarkably, is what they got, at least after 2007 when the Nationalists led a minority administration. The SNP Government had to fight for every vote in parliament. Remember the excitement of not knowing whether John Swinney would push his annual budget through? This was constructive uncertainty that brought out the very best of a new generation of political outsiders such as Mr Swinney, Nicola Sturgeon and Salmond.

Holyrood has reverted to the old pattern of one-party dominance in which the Government pretends to listen to Parliament and then carries on regardless. Legislation is increasingly about buying votes or squaring lobby groups. Meanwhile, many Scots voters like the idea of independence but are, like Turnbull's lion in 1979, a bit feart. It's hard work running a new country, after all. Do we really want the hassle? Isn't it easier to stick with the dependency culture and a Barnett handout every year?

Yes, though partly as a result of that 2011 vote and the referendum it triggered the status quo may no longer be an option. As this column has argued before, the new arrangements for funding the Scottish Parliament under the 2012 Scotland Act will end the fixed formula era and turn every budget round into a struggle. Like the residents of Benefits Street, Scots are going to be forced to get by on less , one way or another. At present Scots, crudely speaking, receive more per head in public spending than they put in through taxation. This was quite fair because the Scots had allowed the UK to have unrestricted access to North Sea Oil. However, after September, Scots will find themselves under growing pressure to justify this spending margin.

I'm not saying this is a reason for voting Yes but it is a factor in the equation. Scots will no longer be able to use the threat of leaving the UK to secure a better deal with London. After September, Scotland could become just another declining "region" of a UK dominated by the London city state. It's possible that the Unionist parties will get their act together and secure a form of devolution that preserves Scotland's spending margins, but I wouldn't hold my breath.

The Yes campaign will seek to turn the £500 question on its head: a No vote, they'll say, will leave Scots £500 a head worse off in public spending. This would not make it any easier for Scottish voters to make up their minds. The clear consensus of the opinion polls is that Scots intend to vote No in September by a margin of three to one.

But, if the Social Attitudes Survey is any guide, it is going to be a grumpy campaign with a disenchanted electorate facing a choice of unacceptable alternatives and wishing that the referendum would just go away. Unfortunately, it won't.