Wisdom teeth blood clot?

What keeps saliva from dislodging a blood clot? I know sucking or spitting will dislodge it, but our mouths are constantly filled with saliva swishing around, what keeps it from dissolving the dried blood? I think of a blood clot as a scab, usually water can soften a scab and have it dissolve or peel off a cut, what is different about a blood clot in the mouth?