With the affordability of het pieds, I would pass on purchasing animals with no genetics guarantee behind them from a reputable breeder.
Don't count on markers - count on the reputation of the person who produced them and is willing to back them up on paper.
For example, if I ever sell my het pied male, I still have the genetics guarantee paperwork, complete with photo of the animal from Adam of 8ballpythons.
Anyone can make a genetics guarantee on paper. That's why it's more important that the person behind that guarantee is reputable.