Actually, many of us are conditioned to expect lies, poor reasoning and offensive behavior from Trump. That conditioning has come from observing Trump prior to the Presidential campaign, during the campaign and after he assumed the Presidency. When someone shows himself to be a bigoted, shallow liar, people understandably assume that his utterances are bigoted, shallow and dishonest.
Perhaps “bias” is the wrong word. The general skepticism of everything that comes from Trump and his staff, including their “alternative facts,” is well earned.