I seem to be using Rescue a lot more lately because of newer players. They ask for some details on the fight, I give as many details as possible to them. They thank me, start the fight and it's obvious they didn't listen to a single word I said - so here comes Rescue.
It's worth it to use in place of a Raise if I see stupid things taking place. I can save at least one person.

I've used it to interrupt LB3 - especially when the tank needs to cast it, or it has to be used on the Tear in the level 50 raid... it's always the damned DRGs too...

If they gripe about it, I let them die, and I don't raise them - someone else can if they want to, or have the ability to, but I'm not going to waste the MP. I try to tell them why I did it, but can't always do that because I'm too busy healing someone else. But, if they can't figure it out, there's nothing more I can do.

Then I get all those 'thanks' given when they know they were about to die, lol.

But to OP - I've yet to see it 'abused' or even misused in situations. Maybe I'm just lucky, but when I have experienced it being used, it's for good cause.