Something insipid is lacking in flavor or interest. You'll probably find the generic poems inside of greeting cards insipid.
Insipid comes from the Latin insipidus, the opposite of sapidus which means flavorful. Because spices and salts are left out, hospital food is usually considered insipid. The most common use of the word is in a metaphorical sense for dull or flat. You might think that your goody-two-shoes cousin is the most insipid girl you've ever met.