These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The 39 Steps
Fair for Its Day / Values Dissonance: Buchan's writing can tend towards the jingoistic when read with modern eyes, but it's nowhere near as bad as some other authors writing at the time; in fact, when compared to works such as Bulldog Drummond, Hannay and Buchan are downright progressive. Greenmantle in particular shows detailed knowledge of and respect for Islam.
Foe Yay: Stumm in Greenmantle. Examples of it include Stumm's man-on-man fight in his rather frilly drawing room and intruding upon Hannay while he's getting dressed. (It's even worse when you read it.)