Practicing Getting the Pretreatment Right on Color T-shirts For My Polyprint DTG Printer

I'm well aware that colored shirts need a certain amount of pretreatment to show a vibrant print using a DTG printer, but I keep focusing on not having a stained box show.
You cannot sell an item with stains on it even though it comes out on first wash.
So that prevents me from putting a sufficient amount of pretreat to get a really nice vibrant print.
I'm going to see if maybe changing my pretreatment from the one that came with the Polyprint Echo2 DTG printer, to the Image Amor for dark colors will help the issue.