What chess openings that are bad or "unsound" can be good if you know well enough.

Is it possible that if you know opening well enough even if its bad or unsound you can still get a decent winrate with it.

Depends on the features of the position, but in general yes.

- you want there to be a high amount of complexity

- you often want it to be uncommon

- you want some compensation for whatever makes it unsound, often tempo but maybe something else

- sometimes it's a position where the opponent has to play a long precise string of engine moves to prove it unsound and so in practice it just isn't a concern

What I think players shouldn't do, though, is cultivate an impulse to just ignore the engine / ignore chess principles as if they mean nothing. Rules have exceptions, but you don't want to ignore them all the time.

Heavens yes. Examine the games of the late great Michael Basman. Splendid chap. Showed us all how vital it is to Think For Ourselves.

Stanford Gambit can be deadly!

Alien Gambit as well!

The Traxler and The Schliemann.

The very fact that they are unsound means that they are often neglected in training by an opponent.

So, if you instantly play your moves, your opponent has the difficult task of refuting the opening only on their time. They are sufficiently complex to cause your opponent to think a lot or lose.