"This latter effect heightened by an unnatural glow which colored his face like a low, incessant fever."
Explanation:
The above sentence from the given excerpt most likely displays that Gordon Sterrett was extremely appalled by his shabby appearance. There is a detailed description of his appearance in the excerpt as 'small, slender, and darkly handsome, unusually framed eyes with long eyelashes with a blue semicircle of ill health' which clearly justifies Gordon's embarrassment to see him. The negative words 'unnatural glow', 'low face', and 'incessant fever' supports this claim effectively and justifies it constructively.