Man.... you don't need to address her with a "you smell good"... you could simply point that you smell something good in the air but you don't know where it come from, she obviously think it's her no? It's about the hint it doesn't need to be obvious... a complimenti doesn't need to be obvious.
Unsless you are an ikeman in a shojo and you can grasp her hair sniff it, taste it, lick it and say whatever and no one will think that's strange lol