No, sir, not that I know of. Poirot's face did not betray a trace of whether he was disappointed or otherwise. 
Poirot may have been disappointed. I have a hard time reading facial responses. 
mnli hypothesis: Poirot may have been disappointed. I have a hard time reading facial responses.  premise: No, sir, not that I know of. Poirot's face did not betray a trace of whether he was disappointed or otherwise. 