[@Limey] Essentially, yes. The rouse check isn't to see if you fail to activate the ability, so much as it is to see if your hunger increases for doing it.
Also, 1 is the minimum hunger you can be at without killing a human. It's not fully sated, but it's as close as you can get without taking a life. 5 would be ravenous to the point of entering a hunger frenzy.

And thank you.