In Thailand, it is considered rude to wear shoes indoors. Shoes are removed as you enter. Therefore, it is common politeness to show bare feet or feet in socks.
I can quite understand a person who lives in Thailand not understanding what a westerner would find unpleasant about people removing shoes.

It is also considered rude to show the soles of your feet to anyone. When sitting, your feet should be tucked in, under or behind you.