Obviously you're right that that sort of unremarkable behavior would never ever be framed in terms of excess or corruption for a Republican candidate or figure, but, to supplement or explain your point, it isn't because of a concerted bias for Republicans or against Democrats. Rather, I think it's because of the culture of the parties, the ideology of the parties, and most of all the standards of conduct that the voters of each party hold politicians to and the subsequently huge disparity in conflicts of interest and corruption between the Democrats and Republicans. And the media seeking to give the appearance of objectivity.
That is, there is exponentially more corruption and conflicts of interest on the right (this is natural, since their ideology is to do the bidding of private power and give private power as much influence over public life as possible), so they necessarily get reported on in larger volume. There is a corresponding desire to increase the volume of such reports on the left for the sake of apparent neutrality.