We can argue that the Pardoner is a good preacher and not a good person because he is very effective in convincing people of the things he says.
This matters to others because it leads to them doubting his authenticity.
In the Canterbury Tales, the Pardoner goes around selling official Church pardons to people that he berates for being sinful. The pardons will then be used to absolve them of their sins.
The Pardoner is an effective preacher because he actually convinces people that they are sinners. He is not a good person because he berates people only to make profit from them as well as trying to swindle them of other possessions.
This mattered to the others who doubted his authenticity because they believed he was simply telling them stories to sell them things.
Find out more on the Canterbury Tales at https://brainly.com/question/848651.