Originally Posted by
Passmethesickbag
GUM is my favourite UA hub, and also the place where US officialdom - customs, immigration, TSA - are at their cuddliest and most efficient.
Guam Customs (not US customs) has such a small territory that they ask different types of questions. For local residents and business visitors, the most usual is "where (who) do you work (for)", and they'll probably know whether it's legit.
CBP Guam is problem-free if either the officer or the passenger is a US citizen of European or African descent, or if the two parties are direct or indirect acquaintances. I've heard Canadians with legitimate work papers getting unfriendly questionings unheard of in the Mainland, Green Card holders of Asian origin (those not yet willing to abandon their non-US careers) trying to maintain residency getting tough questions, and I myself have experienced questioning because of a 350-mile distance between naturalization and passport issuance locations.