Disagree - happiness can run though every particle of misery they arent mutually exclusive everyone who has cried tears of joy even when in pain can understand that feelings don't come singly all the time they are a multiplicity of emotions happiness is often grand its how you value it /view it !
I don't know if I'd agree with the choice of "squalid" in this context. Maybe "wan". Squalid has held a connotation of filth which I never attribute to happiness or its constituents. But I'm sure I'm just demonstrating my bias.
I think squalid works to emphasize the extremes... adrenaline pumps for the crisis and we yawn when the road is smooth...