[rufus]

There are two aspects to a tactic like this:
Exploiting the psychology of a flush board.
The generic necessity of bluffing.

The tactic of semi-bluff to bluff on draw hands has merit in general. I expect that bluffing on all flush cards is a bit much however, so you can get burned if someone notices you're representing too many flushes. You could, similarly, 'OESD bluff' after a flush draw semi-bluff, although it's probably better to do that with an obvious straight-draw river like hitting Q with JT on the board.

The trick is that flush boards tend to be obvious, so players will tend to get the obvious representation.

Notably, this "damned if they call, damned if they don't" is precisely why bluffing increases your equity. Against a game-theoretically correct opponent, bluffs are actually -EV on the current hand, but force the opponent to make -EV call-downs against your legitimate raises.