Louise Blackwell, QC, defending Mr Roache, poured scorn on the idea that the actor turned from "perfect gentleman" to a sexual predator and back again, she told the jury.
Mr Roache, 81, who plays Ken Barlow in the ITV soap, is accused of using his fame and popularity to exploit "star-struck" youngsters in the late 1960s and early 70s.
His trial, now in its third week, has heard from five women who claim he sexually assaulted them when they were 16 or under, either at Granada Studios in Manchester, in his car or at properties he owned between 1967 and 1972.
He denies all the charges and has told the jury at Preston Crown Court he has no knowledge of any of the women.
In the defence case's final submissions to the jury, Miss Blackwell said: "Jimmy Savile has affected, in fact, infected this trial and investigation of these offences.
"The Jimmy Savile allegations, for example, related to when he went around hospitals or vulnerable children's homes. They will know whether he was there, there will be records. One of the things in this case is there is no records."
Mr Roache, from Wilmslow, Cheshire, denies two counts of rape and four counts of indecent assault.
Miss Blackwell said to the jury: "What the prosecution say is that for some weird reason between 1965 and 1972, for no discernible reason, Mr Roache departed from his usual character and behaviour and became a young woman-snatcher, a risk-taker, taking people into toilets. It's nonsense."
The trial was adjourned until Monday.