Accuracy and assessing accuracy

I've just finished Mary Beard's Pompeii, which I enjoyed very much. Somehow she pulls off the trick of being accurate without being dull. At least, I don't know enough about it to know whether or not she's being accurate, but she certainly gives the impression of examining the evidence carefully, and is prepared on many occasions to say that we just can't tell. Maybe it helps that the material she's dealing with is very rich indeed, and has been examined in a lot of detail which she can draw on and assess. But still, I think it's an impressive feat to be careful and leave questions open without sounding dull, and in fact to promote the unanswerable questions as part of the interest of whole thing. I've tried to write for a general audience without over-simplifying, or betraying my academic training, and it's not easy. I've also been involved in giving public tours both at the BL and where I am now. (And I spend more time than I'd like listening to someone give such tours who doesn't really seem to put much premium on accuracy.) I may reread some bits of Pompeii more closely to see if I can work out how Beard does it; it would be a great skill to have.

On the question of assessing authority, here is one of my favourite ever quotations about education, from More Christmas Crackers by John Julius Norwich:

John Alexander Smith, Waynflete Professor of Moral and Metaphysical Philosophy at Oxford, began a course of lectures in 1914 with the following words:
Gentlemen, you are now about to embark upon a course of studies which will occupy you for two years. Together, they form a noble adventure. But I would like to remind you of an important point. Some of you, when you go down from the University, will go into the Church, or to the Bar, or to the House of Commons, or to the Home Civil Service, or the Indian or Colonial Services, or into various professions. Some may go into the Army, some into industry or commerce; some may become country gentlemen. A few -- I hope a very few -- will become teachers or dons. Let me make this clear to you. Except for those in the last category, nothing that you will learn in the course of your studies will be of the slightest possible use to you in after life -- save only this -- that if you work hard and intelligently you should be able to detect when a man is talking rot, and that, in my view, is the main, if not the sole, purpose of education.