Quite welcome Greg. I use these resources daily as a part of my job, and as Slab says, they are only a rough approximation of what the property lines may actually be.

Some of the eastern WA counties are amazingly detailed in the data available on their assessor's website. Others, pretty limited data. Also, some counties have more than one website or process to access map/ownership data.

Which county are you looking for? I may already have that database set as a favorite as I lend across the state.