It often reveals interesting patterns in how attitudes shift over time. But it is just as important in providing some ballast to remind us of how strongly real attitudes often persist when the 'zeitgeist' narrative in politics and the media tells us all we have moved on so that, for example, class no longer matters in British society.
And sometimes it does both at the same time, as today in its findings on spending and taxation.
Take The Telegraph's report today, which projects a sense of a rightwards shift on tax and spend and more generally.
The public has concluded "enough is enough" for increased taxation and raised spending on key services such as health and education, with support at its lowest for almost three decades.
Up to a point, Lord Copper.
Let's dig a little behind that headline claim.
It is correct to report, as the Telegraph does that ...
Only two in five people support increased taxes to fund higher spending on health and education, down from 62 per cent in 1997, while half say taxes and spending should remain the same as they are now, the highest level since 1984.
But does that report not also leave something quite interesting out?
There were three options, not two - even if most nine in ten people who want either higher spending and taxation, or similar levels that we have now. The NatCen briefing shows that it is possible to report them all with just as much economy as a newspaper requires: with one in twelve people supporting lower spending to fund tax cuts.
Public support for increasing taxation and public spending is now at its lowest level since the early 1980s. 39% support this, down from 62% in 1997. Only 8% support cuts. The most popular view, held by 50%, is that spending and taxation levels should stay as they are.
So I am not sure that George Osborne will see the findings as entirely comforting.
Indeed, the great guilty secret of those rather unpopular populists of the Taxpayers' Alliance, Guido Fawkes and every other right-wing group banging the less spending and tax cuts drum has always been what a small niche of public opinion they represent. If you've ever wondered why neither Margaret Thatcher or Ronald Reagan significantly reduced the size of the state as a proportion of GDP, its because they realised that public spending is not nearly as unpopular as their right-wing always claims, even after decades in which it has actively pursued the ideological project of bashing public spending as illegitimate and taxation as theft.
Though support for "less spending and lower taxes" has doubled since 1996 - from 4 % to 8%.
Still, that looks like a long, hard and rather gradual climb to Libertopia.
It is certainly true that levels of support for spending and for redistribution have slipped. The Guardian data-blog usefully sets out the historic patterns and some European comparisons too, providing a chance to look at the new BSA in context.
What might be rather overlooked is how a strong bedrock of support remains: That 81% want more health spending has not escaped David Cameron's notice; 72% want more education spending too, while 67% think government have a responsibility to reduce the gap between the rich and the poor. (There is less support for redistribution to do this: the recent Fabian/Joseph Rowntree Foundation study suggested this apparent paradox reflects a strong public concern to support measures which are pro-equality and pro-fairness, and to reject measures which do not reflect the public's sense of contribution or merit).
One of the long-term trends in the BSA findings has been that shifts in public attitudes have tended to run counter to the dominant political forces of the day. Support for redistribution and higher spending was stubbornly high and increasing under Margaret Thatcher, who (famously for BSA addicts) did not convert the British public to Thatcherism. Yet they fell sharply under New Labour, particularly falling among Labour's own voters.
There is certainly something in the charge that New Labour failed to shift the public environment, in part because it may never have tried. This counter-political phenomenon can, however, also be used to suggest that, while there was support for more redistribution in reaction to the excesses of Thatcherism, that limited public appetite was easily sated by the modest redistribution and taxation of the New Labour years.
The public appetite for "cuts" is certainly more modest still: that historic attitudes pattern suggests that it may be unlikely to deepen over time.
So I wouldn't be surprised to hear the Taxpayers Alliance spinning and celebrating the BSA findings on spending in the next few days. But they might just as well treat them as a rather sobering reality check.
Cutting spending is not nearly so easy and so popular as their megaphone campaigning so often claims.