Is it a good idea to bluff using a multicolor?

[random-player]

Say my next player Bob has a W1 at the 1st position (finesse position) and no card of Bob is clued.
And another player Cathy has a M2, and it's not clued.
I bluff by marking the M2 as Red to get Bob's W1 played and Cathy's M2 saved for later.

I don't know whether this bluff is a good one or a bad one. Because if the bluff makes Cathy think the Red is R2, she may misfire when R1 gets played on board.

Any ideas?

[Travis Hall]

It’s pretty routine among masters. The clue receiver should be aware of all possible cards that the bluff target could be.

Otherwise, you lose a lot of bluff opportunities, many of which will save multiple useful cards. For advanced players, saving cards is far more important than saving a token by playing ambiguous cards without clarification.

[Blacktango]

Yeah, such a bluff is clearly worthy being legal.

Some players may disagree because they have been told that we can't bluff a M card.

1. 95% of the time this is true, but it's not the same as bluffing a card by cluing a M card. So it has nothing to do with your example.
2. In a (very) specific context, even bluff a M card is possible, like almost any clue.