- documenting their BS claims (for your own usage, primarily)
- building trust and credibility with superiors and peers
- biding your time and eventually calling them out on BS in meetings, but only doing so when:
a) they go quite deep into the BS (as they inevitably do)
b) you have firm and credible facts/knowledge ready to use against the BS
c) you are able to pull it off in a calm manner, preferably something that could be perceived as you just asking for a clarification, but still leaves the meeting in a slightly uncomfortable state because the bullshitter's "explanation" seems so obviously fake to anyone with half a brain.
2-3 well-directed questions for "clarifications" like that can be quite lethal over time.