Villa boss Lambert drafted in Keane as his number two at Villa Park at the beginning of July, with the former Sunderland manager combining the role with his position as assistant to Martin O'Neill at Republic of Ireland.
Keane has garnered something of a no-nonsense reputation throughout his playing and coaching career.
Yet Lambert believes that view is often confused with Keane's passion and determination to win, and has urged his team to follow the Irishman's lead.
"I can really trust him. He is a really good football person - a top man. He has been great," Lambert told the Mirror.
"People shouldn't get caught up with Roy Keane being this aggressive person.
"With the career he has had as a footballer - and people forget he had a lot of success as a football manager - what he says is really positive, especially to the young players.
"If they don't take a leaf out of his book then there is something wrong.
"If they don't take in some of the things he says, I think there would be something wrong for them as an individual.
"The good thing about Roy is he will say it as it is. I don't think you can dress something up nicely when it is not.
"He will give you that honest assessment, but we are here to help everybody."
Villa also confirmed on their official Twitter account that goalkeeper Jed Steer has joined Championship side Doncaster Rovers on a three-month loan deal.