At the thrift shop I was at today, they had some of those 96-page "Disney Classic Series" hardcover storybooks from Gallery Books/Mouse Works of the 80s and 90s that are adapted from their films. One was of "The Great Mouse Detective." I remembered reading the Mouse Works reprint from the early 90s, but this was the original 1987 version by Gallery Books, and had some differences in the text.
The reason for the "fail" title is the text here doesn't match the image! If you can't read it, the text says...

Once in the house, they headed for the living room. The tea was good but they waited for Basil for a very long time. All of a sudden a beggar with an old ragged coat and a crumpled hat stormed into the room. In no time, off came the coat, the hat, the false beard and nose, and who appeared but... Basil! Little Olivia couldn’t believe her eyes.
“To lead a successful investigation,” explained the housekeeper, “Basil must go undercover. Yesterday he went out as a priest and tomorrow, well, he’ll go out as a bride!”

However, the illustration clearly shows Basil having just removed his rubber Chinese mouse mask, and still wearing the inflatable "Chinaman" robe. NOTHING like the text describes. Also note the hat Dawson's holding: that wasn't in the movie either.
The early 90s reprint modified the text here so it instead refers to "a figure in a red robe" entering the room, and "off came a mask, and who appeared but... Basil!"
Other weird things in this version of the book include it saying Dawson returned from India instead of Afghanistan (like in the movie), Toby actually talking (WTF?), and when Basil and Ratigan fight on Big Ben near the end, Ratigan isn't wild and feral, and still looks like his normal self. Weird, huh?

Didn't buy any of those books though (I instead got a neat book about the history of Sylvester and Tweety!)