It all really depends on the flavor and the supplier.
Does cherry koolaid REALLY taste like cherries? Not really. But it's a flavor that reminds you of cherries. Liquid is normally the same way.
I've had some flavors that came pretty close to their namesake, but, overall, some are just a stretch.
It also depends on the complexity of the flavor that you're looking for. They won't be able to accurately recreate s'mores, but they can come fairly close to chocolate (and I've heard that there is a marshmellow flavor).
When it comes to
tobacco flavors, you don't have to worry too much. They haven't quite nailed that, yet.
Menthol and mint, being fairly simple flavors, have been the closest flavors I've found to the original.