I've found myself claiming a lot of annoying-to-gets items (Seedbags, bricks, chantrelles) from settlements, be they unclaimed or abandoned. It made me curious as to whether or not other people do the same, and what they would consider abandoned? By what methods would you identify a claim as dead enough to help yourself to any of its goods?
Most reliable seems to be rotted palisade, crops with barely minimap-visible plowed ground, or livestock with empty troughs feeding on nearby grass. In doubt I've looked in chicken coops for starving/dead chickens, before helping myself to (ex-)newbies' delicious blueberries and throwaway leather.