Sentence:  […] (it was the town's <WSD>humour</WSD> to be always gassing of phantom investors who were likely to come any moment and pay a thousand prices for everything) &mdash; “[…] Them rich fellers, they don't make no bad breaks with their money. [...]” 
Meaning of the word marked with <WSD> tags:  A mood, especially a bad mood; a temporary state of mind or disposition brought upon by an event; an abrupt illogical inclination or whim.