Mr McCann said Tony McGill saw him as a "way to make a few quid" and said he received a spate of abusive text messages after he signed for the club in 2007.
Mr McCann was formerly represented by The Sport and Entertainment Media Group (SEM) until he left them because he was unhappy at being hit with a large tax bill.
SEM is being sued, along with Wanderers, for allegedly colluding with each other to exclude Mr McGill from the deal that he claims to have brokered terms for.
Mr McGill alleges that SEM illegally "switched" and purported to represent Wanderers for the 2007 deal so Mr McCann would not pay tax, which the agency denies.
Mr McCann suggested that SEM was guilty of the same practice when he moved from Sunderland to Villa in 2003.
Jeffrey Weston, from SEM, represented Villa in that deal but Mr McCann says he was just told that SEM had done it.
When asked whether that meant he had made a false declaration on transfer documents, Mr McCann said: "Listen, I play football and when you sign a contract, you trust the agents to sort that out."
Dave Sheron, from SEM, and Martin O'Neill have also previously told the court they thought SEM was representing Mr McCann at the time of that transfer.
Throughout his evidence, Mr McCann said he never agreed for Mr McGill to be his agent as he did not want one.
This is despite the court hearing that he made a spate of phone calls to Mr McGill in March 2007 ahead of a meeting with him at the Marriott Hotel in Preston on April 6.
Mr McCann described this as a "chance" encounter despite accompanying him to his private room for a coffee rather than using the hotel bar.
When Martin Budworth, Mr McGill's counsel, put to him several football figures who believed Mr McGill was Mr McCann's agent, the player questioned why they were all "friends" of Mr McGill.
The court also heard how Mr McCann's evidence drastically contradicted that of his Villa manager at the time, Martin O'Neill.
Mr McCann said he spoke to Mr O'Neill on the day of a match against Blackburn Rovers about his future and that he had told him he liked him and that, "tongue-in-cheek", had said he would like to offer him a "10-year contract".
Mr O'Neill denies having such a conversation and Mr Budworth pointed out that he was probably told he was not playing in the day's game, news that prompted an angry phone call to Mr McGill shortly afterwards.
On referring to Mr O'Neill as a "weirdo" in a text allegedly asking Mr McGill to find him a new club, Mr McCann said: "Martin was an interesting fellow.
"He was weird at times but then again I'm probably weird at times, it's no big deal."
Mr McCann was asked why fellow footballer Chris Lumsden told the court that Mr McCann said he felt bad for Mr McGill at a wedding shortly after he had moved to Bolton.
Mr McCann said: "I know Chris well, he's easily led. I used to boss him around the park."
The case continues.
£300,000 fee unexplained
ONE of the agents who supposedly conducted initial talks with Sammy Lee and Frank McParland over the disputed transfer of Gavin McCann could not explain why his firm merited a £300,000 fee for the deal.
The Sport and Entertainment Media Group (SEM) was representing Wanderers, and not Mr McCann, on transfer paperwork relating to the 2007 deal.
Jeffrey Weston, the agent who completed the transfer, has told the court SEM earned their £300,000 agency fee because they put forward Mr McCann's name.
Steve Horner, who claims to have met Mr Lee and Mr McParland in Liverpool in early May, said it was one of the Wanderers pair who suggested Mr McCann's name.
Mr Horner told the court SEM were able to put a value of £1 million to Bolton based on Mr McCann's market value, not a fee garnered from Aston Villa.
The alleged meeting between Mr Lee and Mr McParland and Mr Weston and Mr Horner actually happened much later, according to Mr McGill.
It was to discuss separate transfers of Danny Guthrie from Liverpool to Wanderers on loan and Heidar Helguson, with Mr McCann's deal "tacked on" since to aid SEM's and Wanderers' version of events, according to Mr Budworth.
Mr Horner insisted the meeting took place at the end of the season.
- See our live coverage of today's hearing here.