1.  Advertising is always a dubious means of education, since it involves the testimony of interested parties.

2.  But when we were fighting a dubious war by dubious means, where did that security lie?

3.  It becomes clear that Papa actually was a ruthless opportunist who grabbed land during the Reconstruction, often by dubious means.

4.  Much museum art was acquired by dubious means, if not by outright looting.

5.  Schmidbauer occupies what commentators call a gray world between high office and dubious means.

6.  Kuptsov also accused the central electoral commission of violating the electoral law by trying to boost the turnout by dubious means.