Lee Gardner ran Xpert Roofing without qualifications, insurance or any actual expertise in the trade, a jury heard.
The 29-year-old, who only worked a 16-hour week to protect his benefit payments, paid other equally inept labourers to do the hard graft, Wolverhampton Crown Court was told.
Mr Mark Jackson, prosecuting on behalf of Dudley Council, said: "The workers who put the expert into Xpert Roofing came from the pub and he didn't even know their surnames. He was a rogue trader who used dishonest, deceptive and misleading sales techniques."
Gardner offered to clean gutters for free in March 2014 as a 'thank you' to 77-year-old Christopher Hall for allowing them access to the roof of his next door neighbour in Bowling Green Road, Stourbridge.
He then told Mr Hall that ridge tiles needed to be rebedded in a job that took no more than 45 minutes but cost £500, the court heard. Gardner then told Mr Hall that the whole roof needed repairing and offered to do the job for £5,700.
Mr Hall agreed but phoned the next day to say he had changed his mind. The defendant said he had already ordered scaffolding, tiles, building materials and had arranged men to do the work.
He did not tell the customer he had a right to cancel and 'intimidated' Mr Hall into letting the work start. Mr Hall's son discovered that Xpert Roofing did not trade from the business address given, alerted trading standards and the work was stopped by officials and police on April 1.
A chartered surveyor found so many faults in the work that there was no option but to remove the roof covering and start again. Eight days later Shirley Gulley called Gardner to fix leaking guttering at her home in Ringwood Road, Bushbury after seeing his firm in the Yellow Pages.
He charged £750 for the work, which soared to £1,570 after they allegedly discovered more problems. Checks revealed much of the work billed for had never been done, concluded Mr Jackson.
Gardner, from Brownfield Road, Shard End, who had been previously twice been warned by trading standards about his failure to provide customers with cancellation rights, told the jury: "I never conned no-one."
Mr Stephen Warlock, defending, said: "He is incompetent and was woefully wrong when he thought he could run a business but that does not make him dishonest."
Gardner pleaded guilty to failing to display the special skill, care and honest market practice expected from a trader and was found guilty of four charges of fraud and not guilty of aggressive commercial practice.
He was remanded on bail until July 28 and was also issued with an interim Crasbo, stating he must not go door-to-door offering his services.