I was commenting on another blog once about people who put their feet up on the bulkhead wall when flying in a bulkhead seat on a plane. The views seemed split. Some saw no issues and others were disgusted. I'm personally not disgusted but I still disapprove for other reasons.
One person who commented said he flies internationally all the time and sees it often. He saw nothing wrong with it. I replied to him if he truly flew internationally frequently, he would know how offensive this is to many cultures around the world. For that reason I would never do it on an international flight.
I learned this lesson the hard way. When sitting at a restaurant in Chiang Mai, Thailand a patron approached me when I had my legs crossed with my flip flop off. The barefoot was pointed toward the walking lane in the restaurant. It was not raised more than knee high. The patron, recognizing I was a westerner, informed me in broken English that was not acceptable. I came to learn the foot is considered dirty and never to be raised in a public setting.
It's easy to be USA focused in our values. But I've learned it is important to consider the values of all people when traveling. The problem becomes learning what those values are. That can only come through exposure to the people of the world.
Sometimes not knowing the customs can land you in big trouble. This played out for me during a visit to Sri Lanka. I was visiting a Buddhist temple in the country and snapped a selfie of me with a large Buddha statue. Another person in the temple politely informed me it was illegal to take a photo with Buddha with my back facing him. They told me it was an imprisonable offense in that country and I was fortunate the guards were not there to enforce.
This photo was not taken in Sri Lanka!
I was so relieved! I quickly deleted it from my phone. I later saw a sign to that effect at the airport when I departed. I was so appreciative of the man who informed me before my arrest. I had taken selfie photos of Buddha in other countries without recourse but here the culture was more reverent?
Other cultural tidbits include removing your shoes before entering a temple (the souls of your feet are dirty), and always dressing appropriately and respectfully in religious places around the world.
One thing I try to do in each country which I find respectful but not necessarily a cultural thing, is to learn a few words in their language. That is always well received. I usually learn at least "hello" and "thank you" on the plane ride. In the world of translating apps on our phones it's easy to communicate with most countries, but speaking these few words without aid of an app is a sign of respect (to me anyway).
Respect of cultural differences is a big thing for me. I view other foreigners in disrespect and I shake my head, a bit embarrassed if they are westerners too. Sometimes I educate them and sometimes I don't. I weigh the situation first and calculate the outcome.