When will a motion to disqualify counsel be successful?

But courts have also understood that "[m]otions to disqualify counsel are especially prone to tactical abuse because disqualification imposes heavy burdens on both the clients and courts: clients are deprived of their chosen counsel, litigation costs inevitably increase[,] and delays inevitably occur. . . . At the same time, . . . disqualification of counsel is necessary under certain circumstances, to protect the integrity of our judicial process by enforcing counsel's duties of confidentiality and loyalty. [Citations.]" (City of Santa Barbara v. Superior Court (2004) 122 Cal.App.4th 17, 23, fn. omitted.)