Denbighshire Trading Standards and North Wales Police are warning residents not to get caught out by rogue mattress-sellers.
This follows reports that flyers which offer luxurious orthopedic and memory foam mattresses for unbelievably low prices have been delivered to houses in the Rhuddlan area.
Trading Standards officers warn that the mattresses may be of inferior quality, may not confirm to British safety standards for flammability and the price paid may be over-inflated.
They say there is little prospect of seeking any redress if customers are dissatisfied with any purchase as it is unlikely that proper contact details of the seller will be provided.
Anyone see anything suspicious or have approaches made to them, should report the matter to Citizens Advice Consumer Service on: 0345 404 0506 / 0345 404 0505 (for Welsh speakers) or contact the police on 101.
Councillor David Smith, Cabinet Lead member for Public Realm, said: "These fly-by-night sellers don't care about the risks these mattresses pose, they just want to make a quick buck and leave you with phoney details so they can't be traced.
"These mattresses may be described as memory foam but are carefully wrapped so you have no idea what you are buying.
"They generally fail fire safety tests and are often worn-out, dirty and unhygienic items destined for the tip.
"Anyone offered a cheap mattress on their doorstep should not buy one."