In that case, you could add a 'ContentControlOnExit' macro to your document's 'ThisDocument' code module, coded along the lines of:
Code:
Private Sub Document_ContentControlOnExit(ByVal CCtrl As ContentControl, Cancel As Boolean)
With CCtrl
Select Case .Title
Case "Dropdown1", "Dropdown2"
Select Case .Range.Text
Case .PlaceholderText, "If ""Yes"", Select", "n/a"
.Range.Font.ColorIndex = wdRed
Case Else
.Range.Font.ColorIndex = wdAuto
End Select
End Select
End With
End Sub
where "Dropdown1", "Dropdown2", etc. are the titles you assign to your content controls and .PlaceholderText, "If ""Yes"", Select", "n/a", etc. are the default text and any other options you want to assign the red colour to.