I guess it’s an attempt at an objective assessment of character and attention to detail.
Do you ask what you should do with the cup? Do you offer to take any other empty cups back? Do you remember where the kitchen is? Do you eash the cup or just set it in the sink? Do you interact with any other employees while returning the cup? Do you thank your interviewers for their hospitality?
A measure of how much you will “own” and see through even the smallest of tasks.
Generally, I don’t like gimmicks in interviews. Such as the famous “do you absent-mindedly salt your meals” Ford or some famous industry captain used as their own weird benchmark for suitability. In my experience on both sides of the table, a surprising number of interviewers are looking for their next office friend/partisan. (Which is worse.)
I once went through an interview that was sort of a “good cop/bad cop” routine. It occurred to me later that my demeanor and responses should have been equanimous to both.
As “gimmcks” go, the “coffee cup test isn’t bad: a gentle test of how comfortable you are with the interview and how clear-headed/concientious you are under interview-stress. A decider between two equally strong candidates? Okay. But if it’s one of those hard lines that determine a candidate’s fate for any further consideration, I don’t think it’s a good one.
“I once went through an interview that was sort of a “good cop/bad cop” routine.”
I once had the same experience when interviewing for a driving job with a trucking company.
They would have a three day orientation class upwards of twenty people. We would shed a few people on day one, a few more on day two and on day three the driving test and a two on one interview would shed a few more. The interview was two people firing questions at you like a machine gun. The object was to keep your head while answering the questions as best you could.
They used to weed out approximately 50% of every orientation class. It could be stressful.