I haven't had unprofessional experience with IRS auditors either. When all the facts came out, they were usually more correct than my clients, who often were less than forthcoming with me when reporting their income or expenses. Like CBS, my worst experiences have been with State Unemployment auditors, who were definitely more hostile and wrong than IRS people. I've had to go to supervisors to get proper relief a couple times.
But we are speaking of the IRS as it exists now. Not of the IRS when they receive regulatory powers. My guess is the regulators will not be the same people as the auditors.