The author using physical qualities as if they were the individuals names, making them proper nouns. I think this might qualify as a metonymy
It is a fine technique because it gives the reader a uniquely identifiable name to identify a minor character. It also demonstrates some qualities of the POV characters: wit, intelligence or absence of it, irony.
It can get old fast if over used. An example of where it wasn’t over used is S. King’s The Stand, he refers to Randall Flag as the Walking Dude for a good part of the novel, but that is the only character that is purely referred to by a sobriquet. There is Trash Can Man, but we know his name and know Trash Can is a cruel nickname.
Over use examples might be like if the names connote condescension and snark by the viewpoint character. Some people might think its really funny, but for me I’d likely see it as cheap jokes and it would annoy me.
Also, if every character is given a unique sobriquet by the viewpoint character, like Green Toupee and Limpy and Tee-shirt guy, then it will likely have a distancing effect. If the POV character or the narrator don’t care about the people they are interacting with, then that can back project onto the character and narrator, making them some one I don’t have any interest in.
Of course, there are scenes were it can work, like when it is impossible for the POV character to know anything about the people he or she is watching — a like a new reel or surveillance through a telescope to make up a few examples.