About 85% of the marketing materials that private insurers use for their prescription-drug plans fail to meet all of Medicare's guidelines for those products, according to federal auditors. The marketing products in question include enrollment applications for the Medicare drug benefit as well as explanations of a plan's benefits and rules. The Centers for Medicare and Medicaid Services has dozens of requirements for how the information is supposed to be presented to the elderly and disabled, and auditors found that the materials routinely violated at least one of those requirements.