A person on Quora asks Should you accept an offer of either tea or coffee in a serious meeting or a job interview?. Most say yes. I say no. Here’s my answer:
As an encyclopedia salesperson, (yes—a long time ago), I was taught that you should decline an offer of coffee. Here’s why. Suppose you spend 20 minutes talking with someone about encyclopedias. At the end of your pitch, you have given them your time and wisdom and people feel a need to reciprocate—they feel a little bit guilty that if they don’t buy, your time was wasted—so the need to reciprocate inclines them towards buying. But, if they have given you coffee, then there was an exchange, a quid pro quo, your time for their coffee, and since an exchange was made and your time wasn’t wasted they feel less need to buy.