Playing an opening that is tactically unsound is rather another matter, for punishment is likely to be swift and painful if your opponent knows the refutation. Openings such as the Queen Pawn Counter Gambit (1.e4 e5 2.Nf3 d5), Englund Gambit (1.d4 e5), Jerome Gambit(1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+) involve the early sacrifice of material that is unlikely, against a player of reasonable competence, to bring material or positional compensation...
To go deliberately into such openings or variations is not to be recommended as a general rule. If the opponent is weaker than you, then you should be able to win without taking such risks. If the opponent is stronger, he is likely to know the refutation or find it...