Well ... all I can say is that the 'foundation' drawn by my bees in their foundationless frames is a lovely light cream colour and it smells exactly like - beeswax.
I've never seen bees draw out dark brown wax ?
On the occasions when I render down old dark combs I find that a good few filterings through old flannel sheets leaves the wax a lovely light cream colour not dissimilar to the colour of new wax produced by the bees.
I've heard the old chestnut about how much 'honey' it takes for the bees to make their own wax but who would really, out of choice, put foundation in their hives when it's the colour of **** ?
Even if the bees do draw it out ... one wonders what residues are left in it from it's previous incarnations.
Foundationless ... my way and my bees like it.