Warnings have been issued for homes across the county due to rising reports of cold callers.
Norfolk Constabulary has urged people in north Norfolk and Broadland to be cautious amid recent incidents in these areas.
Seven reports were received on Wednesday of men going door-to-door trying to sell items in Wighton, Station Road in Holt and Knowle Crescent in Sheringham.
Another report was received on Monday of a man offering to sell household items in Wroxham Road in Sprowston.
Some cold callers will say they have recently been released from prison or are in rehabilitation and need money.
A spokesman for Norfolk Constabulary said: "We advise you to close and lock your back door before answering the front door - if you do not recognise the person, speak through the closed and locked door.
"If they are selling something or offering to do any work on your house or garden, tell them you are not interested and ask them to leave.
"We advise that you should never agree to buy goods from, or have work done, by someone that calls unannounced at your door.
"Often such traders don't provide full names, trading addresses or contact telephone numbers, resulting in it being virtually impossible to trace them if there are any problems with the work or goods."
Anyone with information about suspected rogue traders can contact police on 101.