I thought that its flavor depended on how it was brewed.
I have no definite answer for this, but I would suggest that as it's color changes its flavor would change as well. What it's flavor changes to, I would expect that that would be as spontaneous as its color.
From Memory Alpha:
Although not stated directly, there were several types of kanar. In
TNG: "The Wounded" it appeared to be a light purple, transparent drink
served in very small glasses.
In DS9: "The Maquis, Part II" it was seen as the thick, black drink in
characteristic bottles seen in many DS9 episodes.
Then, in DS9: "The Wire" it was a blue, opaque drink in a different
kind of bottle.
In DS9: "The Way of the Warrior", it appeared differently again, this
time it was an orange, opaque liquid, but served in the characteristic
kanar bottles. After that, it finally changed back to the black, thick
liquid seen for the first time in "The Maquis, Part II".
According to an interview with Casey Biggs (Damar), Karo syrup was
used for brown kanar to create the effect of a dark, thick liquid,
which he actually drank. Property Master Joe Longo joked in an issue
of Star Trek: The Magazine (Issue 4) that "... he was drinking so much
he was getting weird, so we started using a thickened sugar-free
Damar's fondness for the spirit, first observed in "Behind the Lines",
was introduced as a way to show an inner turmoil, essentially using it
to drown out his conscience and justify an alliance he knows to be
wrong – indeed, in "Strange Bedfellows", he looks at himself in the
mirror and tosses the drink at his reflection just before helping Worf
and Dax escape. (Star Trek: Deep Space Nine Companion)
In "Behind the Lines", Kanar appeared as a much thinner liquid, akin
to many Human beverages such as wine or spirits. This is in contrast
to "Defiant" where Dukat was shown pouring the drink while being
briefed by Sisko and Odo, where it appeared to have a thick,
treacle-like consistency. The thinner liquid was of an older,
expensive vintage, leading to the conclusion Kanar may thin out as it
The strength of Kanar may also vary greatly. In many episodes we see
Cardassians drinking multiple bottles of it like it was wine, while in
"Behind the Lines" Quark and Damar are both rendered drunk by sharing
a single bottle; considering that they are a bartender and a soldier
they're both expected to have great drinking stamina which suggests
that this bottle of expensive Kanar had the strength of a hard liquor
(which also explains the thinness of it as alcohol has a very low
From this quote we can see that Kanar differs greatly from bottle to bottle.