Feet are not taboo in the United States.
If an American sits by you and crosses one leg on top of the other so the sole of the shoe is facing you, you are not being told you’re lower than dirt. You’re not being told anything at all. The person is simply sitting.
A woman in Turkey was arrested for tweeting a photo of her pretty red shoes on the Quran. In the US, the arrest would not have happened, and not just because of freedom of speech and lack of anti-blasphemy laws. Shoes don’t insult Americans. If you look for pictures of shoes and Bibles, you can find a book cover, a stock photo, and even wedding photos with the bride’s shoes directly sitting on the Bible. The bride wonders if it’s sacrilegious, but it doesn’t stop her from posting the photos because she knows that it’s nothing she’ll be threatened for. The photo wasn’t her idea but she didn’t fire the photographer over it.
When I was in college, one of my roommates held a weekly Bible study. About ten girls would sit in a circle on the floor of our dorm room, Bibles open on the floor in front of them. If someone’s legs started to fall asleep and she uncrossed them and recrossed them the other way, no one gasped in horror if a foot brushed against the Bible.
Incidents in which shoes have been thrown at American politicians and diplomats had to be explained in the media by saying that it’s considered an insult in the Arab world. No one wants to be hit by a shoe, but mostly because it would sting, not because everyone would get the same meaning from it. The closest thing to the meaning in the United States would be throwing a tomato, which means, “You suck!” (That’s why there’s a movie review site called Rotten Tomatoes.)
If you see an American wearing shoes emblazoned with the logo of a sports team, you can be sure the team is one they support. The shoes are not intended as an insult to the opposing team.
Anytime you see an image on an American’s shoes, you can assume it’s an image of something the person loves. The image is intended to express, “Isn’t this awesome?”
If an American puts a deity image on shoes, they aren’t thinking hateful blasphemous thoughts about the deity or Hinduism. It’s appropriate to explain that feet are considered unclean by Hindus, but don’t jump to the conclusion that the person was trying to be offensive. If someone does something knowing it’s offensive, then they’re doing it to provoke a reaction (like the woman in Turkey with her shoes on the Quran). But the same things aren’t universally offensive, and an American putting a design on a shoe is not intended as an insult.
Americans are simply not offended by shoes or feet.