Well, it would necessarily have to be difficult to use to prevent OPness. Because it inherits only your current vector and stays behind the ship, it would be more useful for ships with good acceleration- that way you could charge under cover of mist only if you're able to emit the tar, quickly slow down to let it in front of you, and accelerate again.
Additionally, you could use the vector-inheritance to create decoy clouds- for example, letting a cloud charge ahead of you to see if it gets shot and make the enemy possibly waste a volley. Or if you're fleeing, you could quickly spin around and create several clouds heading in wildly different directions to confuse the enemy.