Whether you say that X=Democratic and Y=Republican or say that X=Republican and Y=Democratic, the following is true.
When an official from the X Party does something awful, many supporters of the X Party try block attempts to investigate whatever that were or to divert attention from the results of such investigation, by focussing on how the Y Party is seeking to gain political advantage from the situation.
And this way of spinning things is a sure ‘tell’ of media bias.