Yeah, with that result Ailani is confident that Grau is a member of the city guard, and that he is lightly inebriated, but not much else.
D'oh, right! This has been a complete DM fail from start to finish, hahahaha!
Yeah, Taking 10 is good for when you really don't want to screw things up by rolling a "1" or "2".
But sometimes it's good to roll here - taking a 10 on that alchemy check to just get above a 20 would have gotten you not nearly as much as that 31 is going to.
I'll post what you learn in the IC thread, and you can decide where to go with it from there.