For some employers, doing extensive prep for an interview and arriving on time isn’t enough. They may also subject you to some serious mindgames and some have been giving insights into the tricks they use to supposedly highlight the best candidates. Trent Innes, managing director of Australian accounting company Xero, bases his hiring decisions on what people do with their glass or coffee cup. “You can develop skills, you can gain knowledge and experience, but it really comes down to attitude,” he recently told The Venture Podcast. “And the attitude that we’ve talked a lot about is the concept of ‘wash your own coffee cup’.” Similar is the Wrapper Test, where a sweet wrapper is dropped by the door of the interview room and the candidate is judged on if they pick it up. This is supposed to provide insights into a person’s selflessness and attention to detail.

Another manager recently shared her way of weeding out those undeserving of a job: they don’t send a thank-you email after the interview. Doing so indicates the person is “eager, organised, and well-mannered”, wrote Jessica Liebman, executive managing editor at Insider Inc, in a post for Business Insider that went viral: “It shows resourcefulness, too, because the candidate often has to hunt down an email address”. Another CEO revealed to the New York Times that she texts prospective employees at 9pm or 11am on a Sunday, “just to see how fast you’ll respond”.

Ruth Cornish, an HR expert, says trying to “hack” recruitment is particularly common in fast-growing companies and tech businesses, “where the culture is very strong. It is a way of identifying whether that person will fit: ‘Are they right for our gang?’” The problem with such tricks, apart from them being potentially unethical, discriminatory and even unlawful, is that companies end up employing the same types of people. “It’s not about diversity or inclusion. If you’ve never been in a world of work before, or your family haven’t, you may not know what etiquette is. It doesn’t mean you’re not a talented person who can’t do a wonderful job at that company.”

Claire McCartney, diversity and inclusion adviser at the HR industry body the Chartered Institute of Personnel and Development, says these tests seem to be an attempt to uncover people’s values and behaviours, “and there are ways that are much more based on evidence” – for instance, asking candidates for examples of their integrity or their ability to work in a team.

There is no rigour to reading into coffee cups and followup emails, says McCartney. “People might respond differently for different reasons – they might be nervous about being interviewed. Not saying thank you to an interviewer doesn’t mean they’re not courteous.” And, as Cornish points out, some employers find a followup email “a bit desperate and annoying”.

For the candidate, these arbitrary tests – which can be as contrived as a challenge on The Apprentice – present more possibilities for post-interview angst. Was your prospective boss impressed when you picked up the greasy Greggs bag – or did you just make her uncomfortably aware that she works amid squalor?