Mystery shopping & investigations

Mystery shopping

We listen to your suggestions for investigations, and sometimes mystery shopping or undercover research is the best way to shed light on a consumer issue.

Actors and mystery shoppers test anything from traders to the quality of care homes, going undercover to explore and reveal issues that would otherwise remain a mystery.

As well as experiencing the issues consumers face, our undercover field workers use hidden cameras and recording equipment to expose malpractice.

We then hold companies and service providers to account, and campaign for better standards where we find need for improvement.

Recent Which? investigative work

Which cover May
  • To test the content of lamb takeaways, we analysed 60 samples from London and Birmingham and found that 40% contained meats other than lamb and seven contained no lamb at all. 

  • Our researchers made 156 phone calls to Isa providers to test whether they could explain the new Isa rules. 7/13 providers answered less than 50% of questions correctly.

  • We sent out five undercover researchers to try 25 mixed NHS and private dental practices, and found that many rated poor or very poor when it came to explaining clarity of NHS and private options, treatments and pricing.

  • Alongside our laser eye surgery survey, we sent undercover researchers to 18 high street laser eye surgery clinics to test their sales techniques and treatment explanations. Six clinics were rates as poor and failed to adequately explain all aspects and risks of the procedure.

  • Our experts covered 1,500 miles, pitching up at 42 shops to test the child car seat fitting services of big high street names.

  • 6/15 nutritional therapists we investigated failed our tests dangerously; one told our undercover researcher not to pursue radiotherapy treatment for cancer.

  • We hired actors to pose as residents in a care home for a week. Our research exposed concerns about lack of activity, health and safety and led to one home being reported to the regulator.

  • Undercover cameras recorded the advice we were given by chains including Halfords, Mamas & Papas, John Lewis and Mothercare regarding correctly fitting child car seats. Worryingly, half of the shops failed to fit them correctly.

Discover the benefits of Which?

As well as testing products and investigating services, Which? offers a range of personal advice from our customer support team, our lawyers and our money experts. Discover the full benefits of Which? by taking out a £1 trial subscription.