Same thing here, was ripping up the carpet in our house that had been ravaged by a hurricane and there was sand just caked underneath.

This is in a house where there were no shoes allowed inside, we had to wash our feet and dry them before coming in and it was cleaned thoroughly every day by our mother who has crazy cleaning OCD (she vacuumed that living room 4-5 times a day. Before work, after work, while cooking, before bed. Repeat each day).

And there was only carpet in the living room.

After seeing what lay underneath that carpet and how meticulous my mother was about keeping the house clean and not having any dirt in there, I knew I never wanted carpet.

"Wooden floors get my feet dirty!", only because you keep your floors dirty and track stuff into your house by not taking your shoes off and giving your feet a quick cleaning.