I recently read Guns, Germs, and Steel, and am now reading Hirohito and the Making of Modern Japan, and I realized they had both won the Pulitzer Prize for General Non-fiction. This got me thinking about what historians think of popular book prizes such as the Pulitzer or National Book Award. GG&S is clearly not held in high regard, but the Hirohito book, as far as I can tell, is good history.
When it comes to fiction, these prizes are generally judged by either fellow peers or those who have an interest in fiction, and while they're certainly not the end all be all for quality, if a book has won one of those awards you know it can't be all too bad. Does the same sentiment generally carry over to nonfiction or biography (or any other history related) categories?
I shall start my answer with an anecdote:
Once a lecturer of mine said "The way to see if somebody is an academic or just a writer of history is to see if the book sells. If it doesn't sell well, they are an academic."
But sometimes really good and popular history books are written by very respected Historians: Tim Cornell's "The Beginnings of Rome". This is when you have a perfect storm of a skilled academic, a skilled teacher, and a very good communicator writing about a subject matter that can appeal to lots of people.
Sadly, many academics can be terrible teachers or bad communicators (at least to people who do not have a similar knowledge already in the subject), and they are often writing about subjects which the public as a whole would find extremely dull. Not many members of the public care about the finer points of Mithraic cults in the provinces in the second century.
If people are reading casually and buy books they want a comprehensive book explained concisely that has a good pace, like "The Beginnings of Rome". But much of what an academic writes is very specific and requires a lot of back knowledge to understand. So nobody who isn't very interested already would ever think of reading it.
So if a history book is popular, it is likely to be comprehensive, well written and regarding a popular topic.
Additional note:
Some celebrity historians (looking at you Ferguson) can be judged extremely harshly by their peers for holding views that most disagree with. So if you are reading a popular history book (and i highly recommend that you do), read about the author as well. Academics do the same when they pick up a new book!
I've read a number of books that have won the Pulitzer Prize. Some of them--Rick Atkinsons' work leaps to mind--are outstanding. They feature great writing and good history. Others--I have some in mind but won't mention them--have featured great writing but shoddy history, usually due to the author's desired conclusion interfering with their research.
So my resulting attitude is that the Pulitzer is a good indicator of very good writing, but not necessarily of good history.
I simply regard those prizes as completely irrelevant, unrepresentative of the actual academic worth of the books in question and simply an activity undertaken to make the people who read those books feel as though they are reading actual historiography.