Do not eat the bread of a man who is stingy;
do not desire his delicacies,
for he is like one who is inwardly calculating.
"Eat and drink!" he says to you,
but his heart is not with you.
You will vomit up the morsels that you have eaten,
and waste your pleasant words.
We come back to the table of verses 1-3. The host, be he a ruler or not, is also observing you. He gives the impression of being generous but is not. He is calculating how much you are costing him. He says to eat and drink, but he is taking note of how much you actually are. He is seething that you are taking him at his word. He thinks you should know better, or else he is risking (in his mind) that you are worth the investment. For that is how he perceives you - a risk investment. He is hoping that his "generosity" will pay off and that he will get back from you more than he has had to put out.
Perhaps you will prove to be a good investment and end up doing favors that you find you cannot get out of. Perhaps you will be a poor investment, thinking that mere expressions of appreciation are enough, only to find you are no longer welcome in his house.
How do you know whether a man is truly generous or inwardly stingy and calculating? You have to do your own share of observation. You cannot let displays of wealth blind you. Observe the man. Observe the way he is with his servants, with his family. Are those who are constantly around him happy and at ease? Are they generous? A truly generous man will rub off on those around him, just as a truly stingy man will do so.
Be discerning. This is what all the proverbs are about. Look beyond yourself and pay attention to what is going on around you. Be a good listener and a good observer. Don't let delicacies cloud your seeing and impair your hearing. Don't let sensual pleasures befuddle your discernment. See through to the giver. Observe him. From him judge whether the delicacies are to be truly enjoyed or turned away. It is the giver, not the delicacies who makes the feast.