A TV aerial repair man was branded "a deceitful, dishonest trader of the very worst kind" as he went on trial accused of ripping off customers.
Keith Matthews is alleged to have overcharged householders, including the elderly, and duped them into having unnecessary work done.
The 59-year-old, of Station Road, Quorn, denies 10 counts relating to four alleged incidents of fraud and engaging in unfair commercial practice.
John Hallissey, prosecuting at Leicester Crown Court yesterday, said: "The defendant is a deceitful, dishonest trader of the very worst kind.
"The sort of trader who gives hardworking honest upstanding businessmen a bad name.
"He uses a variety of names, installing aerials on people's roofs.
"He preys on the vulnerable and deliberately targets the elderly."
The court was told Leicestershire County Council's trading standards department hired an actress to play the part of a vulnerable elderly occupant of a bungalow, which was fitted out with microphones and 12 hidden cameras.
Officers set up an operations room in the garden shed outside the home, in Hospital Lane, Blaby, in April 2011.
Matthew Chapman, a trading standards enforcement officer, said an expert created an easy-to-spot "simple fault" on an aerial cable.
The defendant's employee, Luke Busby (26) – who has admitted an offence of fraud – was filmed at the bungalow after the actress, Frances Harris, responded to a newspaper advert claiming to offer discounts for pensioners.
Busby, of Leicester Road, Countesthorpe, failed to locate the fault and falsely claimed the woman needed a new aerial, which was installed for £95.
He gave her a bill with a false name and address on. The defendant, who was calling himself Gary, was then filmed attending the bungalow to tune in the television.
He handed over an invoice bearing a bogus name and a different false address.
It also had "five-year guarantee", which, Mr Hallissey said, was "worthless and utterly meaningless".
He said Matthews carried out businesses as One Digital and Aerials Direct not to genuinely to repair aerials but for "a fraudulent purpose".
Matthews "aimed to con people" into having work done that did not need doing and to overcharge them for it, Mr Hallissey said.
One of the alleged victims was an 89-year-old man, of Braunstone, who ended up paying £4,900 for aerial repairs and "shoddily" executed odd jobs that the prosecution alleges should not have amounted to more than £490.
Mr Hallissey said a couple in their 70s, of Syston, answered the defendant's advert in May 2011.
Again calling himself Gary, he said a new aerial was needed and allegedly refused to say how much it would cost until after he had fitted it. He charged £260.
"Had they been told the cost in advance, they wouldn't have had the work done and that's why he didn't tell them," said Mr Hallissey.
The court was told that another householder, also in Syston, contacted the defendant.
In March last year, calling himself Stuart, Matthews recommended and installed a signal booster in the attic that was allegedly not needed, charging £100.
Another aerial engineer the couple called in tested the booster to find there was either "a low or non-existent signal" from it.
The householder summoned Matthews back as the original problem was not rectified.
"It became apparent someone who knew what they were doing was going to make it plain he had done a shoddy job," said Mr Hallissey. He ended up giving them a refund.
Matthews is being tried in his absence. The jury has been told by the judge not to draw any inference from him not being present.
Busby, who has yet to be sentenced for his lesser involvement, is expected to give evidence in the trial.
The trial continues.
