Wet Feet in the House . . . Get Used to It
In my experience, if you travel or live with others in Thailand, your feet are going to get wet in the house, every day, several times a day. Get used to it, there's no use in fighting it.
Why Is This?
First of all, Thai people, like most Asians, don't wear their shoes inside the house. They leave them outside the front door. In Thailand, where it is usually hot, socks are often not worn either. So that means bare feet in the house, although house slippers might be worn on them.
But not in the bathroom. The reason for that is that the bathroom floor is often wet. And that is because the shower area is usually not separated from the rest of the room in a Thai bathroom. If someone takes a shower, the entire bathroom floor may get wet. And so, when you go in there in your bare feet, they are gonna get wet, probably several times a day. There may be an absorbent rug just outside the door of the bathroom, to help dry off your feet as you come out.
Of course there are exceptions. The four star hotel we always stay at in Bangkok has the shower area separated from the rest of the bathroom (a big reason it is my favorite) and this is probably common at the more expensive hotels. But usually we stay at very affordable places, where the shower is not separate from the rest of the bathroom.
When it comes time to buy or build my own house in Thailand, you can be sure that the shower will be kept separate from the rest of the bathroom and I will keep my feet dry, except when showering!