With the Finding API, I could add a string condition "Unspecified" alongside my array of int conditions (1000,1500 etc) and I would get results that were all 3 conditions.
The Browse API seems to have some slightly different behaviour in that this sort of setup is invalid:
Furthermore, a fully inclusive conditionIds field with all int IDs will not return any ebay items that are missing the condition field.
Is there an int for the "Unspecified" ID or a way to get listings that are both Unspecified AND whatever integer conditionIds I choose?
It appears the "conditions" filter, which takes strings, allows "Unspecified" but with that filter only NEW and USED are allowed... So this fixes one problem but introduces another.