The risky thing is, in some cases you don't get the full impression of a scent from vials that you can't spray; spraying seems to bring out much more of the top notes. To get a good impression of a 1 ml sample I pour at least half of it on my arm. Unless I know that it's of nuclear strength. And if it's something in the category of light & fresh, I pour the whole sample. So just pour, spread it with a finger, pour some more.