From a non-smoking home but not sure where my parts come from.

Used Parts - the majority of my parts are used so white, trans-clear, blue, yellow, red, light bluish gray, and light gray parts might be discolored from age. And any USED part might have some minor flaws, scratches, or playwear.  Condition of the part if damaged is noted below the item or any extra details. 

Note that modern white parts might have more of a cream tint to them. This is pretty common. 

New Parts - will be inventoried in my store right from the original package. These might have some minor marks from being in with other parts in the same bag. 

If you want new, unused parts buy NEW parts. Also if you purchase a single torso there might be a possiblility where the head you have might be loose fitting. This is pretty common on older played with parts. And I don't test every single torso I have listed with a head. 

Packaging an order - I normally bag color groups together, minifigure parts separate, tiny parts separate, tiles in a separate bag, new parts in one bag, and fragile parts in one bag. I don't bag each single piece individually. Too much waste for our planet already.