I suppose that the long and short of it (for me) would be "anything done shouldn't be decisive to the outcome, and it should be clear to the actors what you're trying to do". Saying "marines inbound" or whatever leaves them in the dark; clarifying that you're trying to have them do something against the Cartel forces gives them enough to work with, if they feel like it -- and if not, well, it's easy enough to explain that away as poor timing or poor execution.
The more arcane the purposes become, the more I feel it's less likely that they'll be taken up, both in terms of integrating into the larger plot well and in terms of CCP knowing what they can actually do with a given hook.
The ECM in the Sansha events is a good example, like a few people have said; an interesting sidenote is that CCP ran with it both ways, at times. At some events TS-F / NQM's using ECCM on the wormholes was run with to great effect; if memory serves, Trytedald was particularly hilarious. Something to the effect of "conduit established" and suddenly e-war elite cruisers, everywhere.