I don't have a problem with single-word-requests that seem non-trivial or can present a common idea or principle that likely has an actual word. I do have a problem with word requests that don't make any sense. Good examples are "false" antonyms:
What is the antonym of three?
What is the antonym of bicycle?
Requests that are far too narrow to be likely are also a problem:
Is there a word for exactly twenty-three animals?
What is a word I can use to describe my company?
Likewise, requests that are too broad get too close to just pounding a thesaurus:
What is another word for blue?
What is a word that describes laughing so hard you are in pain?
But the big problem I have in judging these things that, sometimes, there is such a word and someone happens to know it and turn the entire question into a fantastic vocabulary lesson. My current best way to determine the quality of a single-word-request is by the quality of the answers.
On the other side of the coin, an asker's persistent rejection of perfectly fine examples due to the unspoken circumstances is just annoying.