Consider the following situation:
B is negotiating with a group of foreigners
C who are widely (and with a reason) suspected of having an "alternative" view on business ethics.
B thinks that the crooks might betray themselves by talking to each other in their language which
B does not understand, so he asks his friend
F (who is a native speaker of the foreign language) to listen in on the negotiations (from the next room when negotiating in person or on a second phone line when negotiating over the phone). So,
C do not know that there is a third party
F listening to the negotiations.
B records the conversation (without
C's knowledge) and lets
F listen to it off-line.
If this behavior unethical?
Obviously, the answer may depend on the country in question (I have the story from
F who was quite proud of his role), so let us limit ourselves to USA (and the West in general).