The psalmist prays for “good moral taste/judgment” (Hebrew taam) in 119:66 — along with good knowledge. We might ponder what we have a good taste for:
Many of us have good taste in food — we know the difference between a store-bought broth and home-made stock; some have good taste in cars — we know the strength of a well-made car; others have good tastes in clothing — they not only coordinate one article with another, they know what to wear and when and where to wear it. Others have good tastes in pens — we know Conklin from Conway Steward and Mont Blanc.

The psalmist may have had some of these tastes, but he wants good “moral” tastes. Once a friend told me that he no longer struggled with right from wrong but rather the better from the good. That is what the psalmist longs for: a taste for what is good, for what is wise, for what is the best judgment in particular situations.
This psalmist longs for God to teach him good taste because he trusts in God’s commandments. We will never develop good taste until we listen to God’s tastes so we can make it our own.