If so, the first three premises are contradictory - Bob says Gloops are plink 0.7 of the time, and almost all of that time he is correct, so p(Gloops are plink) > 0.4.

Thankyou and well spotted. Those completely arbitrary magic numbers don't stand up to a second glance. In particular 0.7 is just silly. If you already know what the expert is going to say you barely need the expert to say it and so cannot be in a state of knowledge such that p(B) is so low. I'd better change them.