IMO basses are tools. Buying a used bass is like buying used mechanic's tools. Some mechanics tools are bought to be used in the brutal day to day business of fixing cars and equipment. That takes it's toll on them. Care and maintenance by the owner plays into it too as used & abused tools offer poor performance and many frustrations. Some tools are owned by hobbyist mechanics who use them occasionally and care for them passionately. Used basses fall under the same general conditions so it matters greatly what you are buying and who you are buying it from. IMO there is nothing nicer than a new set of well made sockets or a new well made bass.