Non-practitioners writing opening books

Before buying a book on a chess opening, I usually search various databases to verify whether the author actually plays the opening. If there is no trace of the opening being a part of the author's repertoire, I will probably will not buy the book. On the other hand, few players want to make their opening preparation secrets a public affair. Therefore, I am not surprised to note that many opening books were in fact written by non-practitioners.

I am curious whether others do such "research" prior to buying an opening book, or am I being a bit paranoid?  

I figure anyone who was allowed to publish an opening book knows better than i do. The only research I do is reading amazon reviews, and maybe sounding out the group dedicated to that opening here.

True, some openings are "static" enough that even a book by a non-practitioner would probably be safe; I have in mind openings such as the Four Knights, the Ponziani, Center Game, which are rarely used at the highest level.

I suppose you had McDonald's book on the KG in mind...