Does 갯사람 mean "dog people"?

 ANSWER: No. It means "people" (사람) who live in a "seaside village" (갯마을) on the "shore of an estuary or inlet" (갯가), where one will often find "tidal mudflats" (갯벌 or 개펄), which are sometimes called 갯뻘 or 개뻘.

Here the word 개 does not mean "dog." It is a pure Korean word that means "inlet," "cove," or "estuary." And 벌 or 펄 means "field," so 갯벌 and 개펄 literally mean "estuary/inlet (개/갯) field (벌/펄)," where you will find 개흙, "the slimy mud or silt on the bank of an inlet or estuary."

By the way, 갯바람 translates as "sea breeze" but literally means "estuary/inlet (갯) wind (바람)."

From Dong-A's Prime Korean-English Dictionary (1998)