Chinese border officials asking U.S. visitors about their political affiliation

For immigrants, not short-term visitors. Membership on the CPC would be incompatible with naturalization in most countries I would think; such a person has to take two fundamentally incompatible oaths:

> It is my will to join the Communist Party of China, uphold the Party's program, observe the provisions of the Party Constitution, fulfill a Party member's duties, carry out the Party's decisions, strictly observe Party discipline, guard Party secrets, be loyal to the Party, work hard, fight for communism throughout my life, be ready at all times to sacrifice my all for the Party and the people, and never betray the Party. [1]

This seems incompatible with naturalizing in Canada, for example, assuming the person still adheres to their oath and the party:

> I swear (or affirm) that I will be faithful and bear true allegiance to His Majesty King Charles the Third, King of Canada, His Heirs and Successors, and that I will faithfully observe the laws of Canada, including the Constitution, which recognizes and affirms the Aboriginal and treaty rights of First Nations, Inuit and Métis peoples, and fulfil my duties as a Canadian citizen. [2]

Generally, it's a potential issue for anyone with dual citizenship, or membership in any group that requires unconditional and irrevocable loyalty (such as some political parties). If the two groups come to conflict, it may be literally impossible to not betray one of your oaths.

[1] https://en.m.wikipedia.org/wiki/Chinese_Communist_Party_Admi...

[2] https://en.m.wikipedia.org/wiki/Oath_of_Citizenship_(Canada)