There are those who even try to induce a PKI customer to do just that. Their logic goes: (1) you have an ID certificate, (2) that gives you the keyholder's name, (3) that means you know who the keyholder is, (4) that's what you needed to know. Of course, that's not what you needed to know. In addition, the logical links from 1 to 2, 2 to 3 and 3 to 4 are individually flawed. [We leave finding those as an exercise for the reader.]