McGinn scored the only goal in Scotland's 1-0 win over Haiti in Boston, ending a 36-year wait for a World Cup victory and giving Steve Clarke's side a winning start to the tournament.
It was Scotland's first appearance at a World Cup since 1998, and McGinn's deflected strike in the 28th minute proved decisive as the Tartan Army held on for the points.
The Aston Villa captain has established himself as one of Scotland's most important players in recent years, having lifted the Europa League with his club just weeks before travelling to the tournament.
Keane, working as a pundit for ITV, had questioned McGinn's consistency in the build-up to the Haiti match.
"McGinn is one of these fellas, when he has his bad days, he does look like a pub player. When he's off it, he's shocking. I've watched him long enough. When he's bad, wow. But you'd have him in your group. Absolutely."
The comments drew attention in the build-up to Scotland's opener, but McGinn was unfazed by the criticism when asked about it afterwards.
"He's getting slagged for that, I didn't think what he said was that bad! He followed it up with something complimentary."
McGinn went on to acknowledge there was substance behind Keane's observation.
"He was right. I actually think the amount of games I'm looking like a pub player is getting less and less as I get older; I try not to have as many games like that and try to be more consistent. But I didn't think it was too bad."
The 31-year-old added that he had taken the comments as a form of flattery rather than criticism.
"People were saying, 'Oh, did you see what he said?'. I just thought it was quite nice they were talking about me!"
Scotland's win lifted them to the top of Group C after Brazil and Morocco played out a draw elsewhere on the same day, and McGinn agreed with Keane's assessment that his side have little to fear in their remaining fixtures.
"He's right, we've got nothing to fear going into these games. All the pressure's going to be on Morocco, all the pressure's going to be on Brazil."
Scotland will need results against both of those sides to give themselves a chance of reaching the knockout stages for the first time in their history, a target that now looks more achievable after their opening win.
McGinn's goal, his first for Scotland since November, also made him the oldest player to score for the country at a World Cup, underlining the senior role he continues to play within Clarke's squad as the tournament progresses.