There's no such thing as a normal-appearing snake being "het for bloodred." And yeah, I realize that many people sell snakes under this name. "Diffused" is a simple recessive genetic trait. But this is only one element of bloodred which is diffused + hypererythrism (excessive red pigment). The hypererythrism aspect is not recessive, rather it is variable (not like a simple recessive genetic trait, which is an "all or nothing" expression). Each snake carrying the trait will vary in the amount of red coloration it has.
No normal-appearing snake can be het for a morph that expresses two or more traits (snow, striped hypo, ghost, amel motley, etc.). A normal-appearing snake can be DOUBLE HET for a a trait that expresses two morphs, but in the case of bloodreds, this would not apply, since only one of its traits (diffused) is recessive. The other trait (hypereyrthrism) is not recessive, therefore a snake cannot be "het" for it.