One of Roache's alleged victims told Preston Crown Court how actor Peter Adamson, who played Len Fairclough in the soap, told her Roache would "lead you astray".
The witness claimed Roache indecently assaulted her when she was around 14 years old during a visit to Granada Studios in Manchester.
She told the court Roache had arranged for passes for herself and her younger sister and he groped her in a room after being led past the Rovers Return pub on the set.
Her sister claims she was abused by Roache on a separate occasion.
On Monday, she was cross-examined by the defendant's lawyer, Louise Blackwell QC, and claimed that Mr. Adamson made the "cockroach" remark about the actor while she was at the studios.
"It was Len Fairclough that made the comment," she said.
"Because when he said it he looked directly at him and he looked at us and said "You want to keep your eye on him, he will lead you astray' and he called him 'cockroach'".
"Len Fairclough said that he would lead us astray. He called him a cockroach with a capital C."
The court heard that the alleged victim and her sister would sit on the steps outside the studio in the summer holidays in the mid to late 1960s, along with other girls and boys who were autograph-hunting.
But on one occasion after being invited inside the studios, Roache took her to his dressing room and indecently assaulted her.
She told police: "He was like an octopus - hands everywhere."
Roache, 81, of Wilmslow, Cheshire, denies two counts of rapes and five counts of indecent assault involving five complainants aged 16 and under.
The alleged offences are said to have happened on dates between 1965 and 1971.
The actor was charged last May with two counts of rape on one alleged victim, with the publicity that following leading to the four other complainants coming forward.
The witness was asked by Miss Blackwell about press interest in her story and reporters visiting her house.
She said her sister had "two visits from the Mirror" and had been offered £25,000 for her story.
The witness added she was visited once by a reporter from The Sun, but the only money mentioned was a donation of an undisclosed amount to a charity.
"I know what's going through your mind," she told Miss Blackwell, "and it's not going to happen, because I did not want money."
She added: "If I wanted money I could've sold my story but I have not sold my story. I have spoken to nobody except those who should know."
The trail continues.