MD Mafo-Dresden is alleged to have asked participants to pay a fee or take out a subscription to a TV magazine at an inflated price, in order to be eligible to receive free samples of products ranging from toothpaste to mobile phones – but none of the promised items showed up.

The board of arbitration for German market and social research has accused the firm of “gross” misconduct, and Dresden police are dealing with complaints from 67 people, but so far no one has been able to locate the people behind the firm. Many of the victims are low earners such as pensioners, welfare recipients and unemployed people.

The consumer centre for the state of Saxony said signing up to be a product tester was no guarantee of receiving free goods – and warned consumers that products on test could be things like toothpaste and pencils as well as mobile phones and flat-screen TVs. Meanwhile companies running such operations can profit not only from the fees charged but also by selling data from the questionnaires completed by would-be participants.

The centre advised consumers to be wary of any offer that involves paying money to earn money, and to be cautious about who they give personal data to.