There is a limit to the amount of CRUD the merchants keep, so some of it will go, but not quickly, you will have to wait until the start of the next act before they are clean again.
What worked for me was this.....
I get rid of my stuff in the Battlefields. You will notice that each merchant specialises in a particular type of product. since I never buy potions, I sell all mr "crud" to the potion seller (Woman in green who's name escapes me). If she hasn't got enough money to buy it all, then quickly warp in and out of the battlefield to refresh the merchants inventory.
You can then browse the other merchants who might have stuff you want, totally "crud" free. and not worry that the potion seller may have something you want.
