

Chlorine for water treatment. Cheap and useful where clean water is difficult to come by and where water is stored for long term use. Also very common to buy if you have a pool. But maybe for middle class households it is not as common of an item - except perhaps in areas were pools are common enough in middle-class homes.
Just a guess!
I tried to make a comment on that site and it was simply not possible for me to do it while implementing basic privacy-preserving techniques like using a VPN or even through a pre-paid sim card. I think that their ‘anti-bot/anti-spam’ mechanisms push users to de-anonimize quite strongly. Honey pot makes sense to me.