“If ever a nation has been deceived by a man, the American nation has been deceived by {George} Washington. Let his conduct, then, be an example to future ages. Let it serve to be a warning that no man may be an idol. Let the history of the Federal government instruct mankind that the mark of patriotism may be worn to conceal the foulest designs against the liberties of the people.” – James T. Callender, Newspaper Owner and Supporter of Thomas Jefferson

Identify a potential point of bias in the source quotation

Newspaper Owner and Supporter of Thomas Jefferson

As Ms. Sue had pointed out, the author of the article is a supporter of Thomas Jefferson, according to the text. You can also look for key literary terms, such as "deceived" and "idol," since there is, essentially, no evidence backing up that he claims to be an idol, or that he deceived the American people.

I still dont understand

Can we trust a politician to say anything good about an opponent?

yes

Can you give me an example so i can understand it better

President Trump never says anything good about any of his opponents.