Gothic Line: Domestos is not a real island, over here it is a bleach product used to clean toilets.....
I can understand the confusion, I don't know whether Domestos is sold in Portugal but I can't recall ever seeing it in Brazil. Most of their other cleaning products like Omo, Surf, Comfort etc do appear on supermarket shelves.
I suspect they've avoided marketing Domestos as such because the name bears a similarity to 'domestica' the person most likely to be using the stuff in any well off household. No simple housewife wants to be reminded of the fact and no maid wants to be equated with a bottle of of bleach.
Even in Australia, more often than not, my wife gives me shopping instructions in Portuguese and on occasion by brand name, so I have to equate 'Bombril' with steel wool
and perform other acts of mental gymnastics in various aisles of my local supermarket.