i don't know whether you write for fun or profit, but there's lots of 'ly' adverbs. it's adverb hell. the rule is don't tell, show. and adverbs tell.
this is the best sentence as it shows what's happening. not a single adverb.
"Fifteen minutes later John sits, observing the other patients in the waiting room: the happy little girl being rewarded with a lollipop by a doctor before leaving with her father, the smiling teenager with a bandaged arm, and the elderly man consoling his suffering wife in her wheelchair."
(i moved a comma and put a missing word in. i couldn't help myself )
using words like 'lividly' and 'inhumanely' is telling the reader what to think about the character or situation, when you should be showing them the person or situation and letting them make up their own mind.
being told is boring, being shown is interesting.
I see where you're going with that, and I think it's good advice.
I do see what you mean about calling his murderous intent "inhumane"; let the reader decide what it is. But I don't think my writing style is bad or hard to follow.