Transitive or not?

Here is a good one:

If I believe everything that Bob says and Bob believes everything Sally says, then I should believe everything Sally says....except Bob might not repeat something Sally says. I cannot really be said to believe something that has not yet been said.

This is an example of information moving around that seems to lie near the heart of transitivity. Compare with: If I know everything Bob knows, and Bob knows everything that Sally knows; then I know everything Sally knows.