Tom Weisser simply seems to have been thinking that if he can get away with stuff like that, why not? Why bother?
I guess he was cynically aware of the lack of spaghetti western information (in America at least), and along with spreading real information he actually exploited the genre’s unknown status. Or at least used it as an excuse for not doing his homework (checking facts, naming sources, actually watching the movies, etc). Selling more Video Search of Miami tapes seems to have be the book’s hidden agenda. European horror films were hot underground items in pre-DVD times and Weisser never fails to mention the giallo / exploitation / horror credits of SW filmmakers, stuff that’s often out of place in a western book and appears to be there for the purpose of encouraging European horror fans into buying European westerns. This reaches absurd proportions when Weisser always singles out the “excellent” cinematography of exploitation director / DP Joe D’Amato that’s often totally workmanlike and dull, and it all feels like an attempt to get Italo-horror fans interested. I doubt if this was successful.