I can give you quite a few detailed examples, but you'll need to allow me a wee bit of time to get out the books in question and give them a quick scan through.
With James Cowan, he never really put himself forward as the expert, he was more the inquisitor initially.
I think i made a comparison with HG and James Cowan on an early posting when i joined the forums, in which i quoted from James Cowan's books preface in which he explains his passion for Glasgow and his inquisitive nature which led him to want to learn about the city.
"From Glasgow's Treasure Chest" as you may be aware, is basically a collection of James Cowan's newspaper columns on discovering "Hidden Glasgow" as "Peter Prowler" from the Evening Citizen which he wrote in the early - mid 1930's, which was printed as a collected volume in 1950 or thereabouts.
In the book at the end of some articles, he has added at the time that the volume was being prepared, notes on what had been found out since the article was published. Also letters from readers who wrote into his newspaper with more information or correcting points etc were added.
The book as i said, came out in 1950 or thereabouts and was reprinted several times shortly thereafter. I do not think there has been further impressions since the early 1950's.
With regards to some of his articles on Mount Florida, Deaf and Dumb Institute, a hidden garden off Great Western Road, a building in Argyle Street etc, and a good few more, i have noted, not so much errors - i would like to call them more like assumptions which he has left a bit open ended until further information came to light.
With Jack House if you read an early edition of any of his Glasgow book's and then look at the same book - later edition you will find that information has been added and corrections made due to new information coming to light.
Again, it has been some time since some of Jack House's books have been revised / updated, so it is only natural that with the passage of time and the more openly available resources that things which may have been assumed, taken as the accepted history have been clarified and corrected.
There is one particular passage in one of his books where he gets into a bit of a muddle about the history of the Saracen's Head. I'll have a look for it later and post the bit i am referring to.
Jack House for me was a good story teller and undoubtedly he did a lot for preserving and promoting the history of Glasgow, and he no doubt turned a lot of people's interest towards the history of their City.
But for me a lot of his stuff seems to be the same material chewed over again and again. But it was a winning formula, so why not repeat it.