IT would be fantasy to suppose George Osborne was bluffing when he ruled out the SNP's currency union proposal, Chief Secretary to the Treasury Danny Alexander told a Holyrood committee on Wednesday.

The Chancellor's position was definitive, he said, and there was no point pretending anything different. Oh, no. If it's bluffing you're after, he added, Alex Salmond is your man. Mr Alexander simply refused to believe the First Minister's warning that an independent Scotland would not shoulder its share of the UK's national debt if Mr Osborne rejected a formal pound-sharing deal because, he claimed, it would damage the country's creditworthiness, increase the cost of borrowing and put £5200 on the average annual mortgage repayment. Of course, it's a very similar argument to the one being used by Mr Salmond when he claims Mr Osborne is bluffing because, if push came to shove, he would not wish to saddle English firms with the added costs of trading in a new Scottish currency.

The Highland MP put in a polished performance fielding questions from MSPs. He didn't give much away when it came to our turn either. In a post-meeting mini-press conference, that sort that's daftly dubbed "a huddle" nowadays, I suggested to him that, with both sides in the independence debate accusing each other of bluffing, things were perhaps getting a little confusing for voters. An adept politician, Mr Alexander contrived to answer a slightly different question and that was that.

I'd still like to know what he thinks, though. The debate has reached a stage where voters not only have to factor in the possibility/probability that, despite all claims to the contrary, both sides are adopting negotiating positions; they also have to take a stab at how strong a hand each has. Already difficult economic judgments are being overlaid by political considerations. For example: if Scotland votes Yes, could the fate of a currency union be sealed by George Osborne's inability to back down, irrespective of the plan's economic merits? Voters are about as far as they could be from the clear, factual, impartial information most say they need.

All this is why the STUC's A Just Scotland report, published a day after Mr Alexander's visit to Holyrood, is so important. Clearly and impartially, it bypasses the entrenched positions, debunks the overblown rhetoric and provides a realistic assessment of various possible outcomes following a Yes or No vote. Refreshingly, it comes at the whole question of independence with a genuinely open mind. The aim, as the report says in its introduction, is to consider what's best in terms advancing the "collective values" of the trade union movement, promoting social justice and reducing inequality.

On the currency, the issue that again dominated the week at Holyrood, it argues it was unhelpful of the UK Government to rule out a currency union. The Scottish Government, though, must take a share of the blame for the current stand-off by refusing to acknowledge the disadvantages of the policy while exaggerating the benefits. The STUC calls on Mr Salmond to "develop a much more coherent and compelling case" for the policy. In the meantime, it says, he should assess the alternatives.

On Europe, that other recurring referendum flashpoint, the UK Government is accused of failing voters by refusing to seek clarity on an independent Scotland's possible terms of EU membership. The Scottish Government has "grounds for optimism" it could negotiate opt-outs from the euro single currency and Schengen travel area, the report says, though it is being unduly optimistic that it could reach such a deal quickly.

The report raises questions about whether the SNP's economic policies (the STUC is unimpressed by the prospect of a 3p cut in the rate of Corporation Tax) would deliver its promised improvements to benefits and pensions (which appeal to the unions). For the pro-UK parties, the biggest criticism is the lack of a clear vision to extend devolution in the event of a No vote.

On these and other key issues, A Just Scotland doesn't make entirely happy reading for either side. That alone should be enough to commend it to all open-minded, undecided or downright confused voters.