Tar With The Same Brush
(transitive, idiomatic) To characterize using the same undesirable attribute, especially unjustly.
Example: 1865, Charles Dickens, Our Mutual Friend, ch. 6:
They are both tarred with a dirty brush, and I can't have the Fellowships tarred with the same brush.
1900, E. Phillips Oppenheim, A Millionaire of Yesterday, ch. 41:
Were you tarred with the same brush as those canting snobs who doomed a poor old man to a living death?
1920, Lucy Maud Montgomery, Rilla of Ingleside, ch. 14:
Susan still persisted in thinking that poets and tramps were tarred with the same brush.
1922, James Joyce, Ulysses Chapter 13
Place made me think of that I suppose. All tarred with the same brush Wiping pens in their stockings.
2008, Terry Sweetman, "Kevin Rudd's public service demands nothing new," Courier-Mail (Australia), 6 June (retrieved 21 May 2009):
And few would distinguish between state and federal public servants, tarring them with the same brush of disdain.