This is not a subjective question as the question asks about the technical accuracy of a book and should be acceptable
They are. It's not hard to find perfectly good questions on Stack Overflow regarding the technical accuracy of something presented as fact in a book.
However, attempting to bite off an entire book in one question is going to be a bit broad. Even if the book is "Mr. Bunny's Guide to ActiveX*".
As Bill stated:
If you posted the specific code example from the book and asked if the problem illustrated was fixed in a later version of the language (the specific version you're using, preferably), I think it would probably be okay.
To understand why trying to tackle the question of an entire book's accuracy in one go is a bit sketchy, imagine that the sort of question Bill outlined will attract a really good answer. Now imagine that the small book you're interested in has only 5 chapters, with only 3 code samples in each chapter. A decent answer now needs to cover the accuracy of 15 different bits of code, preferably with references, explanations and such.
Even assuming you catch the eye of someone who reviewed the book prior to publication, and they still have all their old notes... This is a fair bit of work to be asking for. And we're not even getting into the actual text of this small book yet!
So let's be honest: what you're gonna get is at best an ad-hoc collection of errata that folks observe while reading the book.
*The only book you should ever buy on ActiveX, or bunnies.