For the people he interviews? MediaBistro's Fishbowl D.C. notes that recently broadcasting from the campus of Ole Miss, Matthews interviewed a number of student members of the group Concerned Youth of America. One of them was Matthews' own daughter, although Matthews didn't inform viewers.
Sadly, as Cernig at Crooks and Liars notes:
It's such a small-beer breach of what passes for journalistic ethics nowadays as to go almost un-noticed, although in the halcyon days of journalism it would probably have gotten him fired or at least earned the censure of his peers.