She was described in court as a "very close friend" of Jacqui Bradley and is now flatting with her in Ponsonby after Mike Bradley died last year.
Defence lawyer Ron Mansfield admitted Smith was not truly independent, but said she was ideally placed to reveal what went on at B'On.
Although a Crown witness earlier labelled Jacqui Bradley as "the brains" behind the couple's business, Mansfield said yesterday that Mike Bradley dealt with investor funds.
"That was his forte ... Mike Bradley would deal with the placement of those monies, he would deal with the management of those monies."
Mike Bradley made himself out to be an entrepreneur, while his wife spent "quite a considerable time bringing up the children", Mansfield told the court.
The defence lawyer said that since Mike Bradley's death some investors who lost money when B'On folded had changed the focus of their evidence.
"It seems since Mike's passing many of the investors ... rather than focusing on Mike, started to focus their energies and criticism on Jacqui Bradley," Mansfield said.
"Some are particularly bitter and one can't blame them for that."
Yesterday was the first real indication the court got of Bradley's defence against allegations that she fleeced 28 investors of around $15 million.
Bradley, who faces 75 Crimes Act charges and is accused of running a Ponzi-type scheme, has been on trial for three weeks.
Smith will continue giving evidence for the defence today before undergoing cross-examination by the Crown.