What is the standard for establishing bias and prejudice against a judge?

Judicial "'bias and prejudice must clearly be established by an objective standard.' [Citations.] 'Judges, like all human beings, have widely varying experiences and backgrounds. Except perhaps in extreme circumstances, those not directly related to the case or the parties do not disqualify them.'" (Haworth v. Superior Court (2010) 50 Cal.4th 372, 389, italics added.) "'The "reasonable person" is not someone who is "hypersensitive or unduly suspicious," but rather is a "well-informed, thoughtful observer."' [Citations.] '[T]he partisan litigant emotionally involved in the controversy underlying the lawsuit is not the disinterested objective observer whose doubts concerning the judge's impartiality provide the governing standard.'" (Ibid.)