Success doesn't always have to be scot-free. You can also have a success with complications, or some cost. If a player rolls a critical, then usually it's considered to be definite success, without any negative effects. This is when you can pull out out-of-game costs...
Commentary by memnarch (who has not seen the movie)
Excellent, now there's even proof that BB-8's not been spotted. Hopefully he can stay out of sight enough to be able to pull a trick of some kind. And that 00-B doesn't notice in time to stop the trick.
I also can't quite tell if Phasma is claiming there was never a bin, or if there just wasn't one found. But we're back to poems now, so either way it probably means that BB's in the clear for the moment. And really, it wasn't that bad a cost; it's not like it was poetry by Paula Jennings from some English locale or something.
Transcript
General Phasma: I am your shadow at morning striding behind you. Your shadow at evening rising to meet you.
General Phasma: I will show you fear in a handful of dust.
BB-9E: There was also a suspicious looking waste bin following them.
BB-8: Oops! I keep still and try to look like rubbish.
GM: Roll for Stealth.
BB-8: 20!
First Order Officer: We didn’t find any such bin, Ma’am.
General Phasma: A cavity, a cavity, what’s in that bin’s concavity? There never was a bin of such deceitfulness and suavity.
General Phasma: It always has an alibi, and one or two to spare: At whatever time the deed took place—the waste bin wasn’t there!
BB-8: Did I get away with it?
Rose: Yes, but at a terrible, terrible cost.