Hello,
In case of using inner and outer form with the kendo-combo-box outer form sets dirty after setting datasource value: http://dojo.telerik.com/IBIxI/2
It is reproducible when ng-model has null value and works fine when it has any other value.
The same behavior for kendo-drop-down-list directive that used with select tag. ng-model has any value except null in this case: http://dojo.telerik.com/IvUKo