The aspirational first lady of the United States instead condemned her husband’s opponent as someone whose public statements could not be compared.
In an interview with CNN on Sunday, she told Jake Tapper that after president Trump, “you cannot even say the word gaffe”.
“Oh, you can't even go there,” Ms Biden replied after the CNN anchor commented on her husband's occasional slip-ups in public, saying he “has been known to make the occasional gaffe.”
She responded: “After Donald Trump, you cannot even say the word gaffe,” and added that "[it’s] Done. It's gone."
The CNN host, who asked again whether or not "The gaffe issue is over", was told "[it’s] Over. So over."
It comes after Mr Trump suggested on Sunday that Mr Biden - without basis - was taking performance enhancing drugs prior to campaign appearances, and would do so again when the pair meet on Tuesday night for a first televised debate.
The president, himself aged 74, has at the same tried to paint his 77-year-old Democratic opponent as someone who was senile - with the nickname “Sleepy Joe”.
Disputing that portrayal on Sunday, Ms Biden said her husband was ready to debate the president on stage, saying: Oh my gosh, yes he’s ready.”
“One of the things I'm excited for is when the American people see Joe Biden up there on that stage, they're going to see what a president looks like," she told CNN.
The two candidates, both of whom have argued over their cognitive abilities, will take part in three live debates before the election in 36 days time.