I've tended to assume that the tails "flatten" better than those on
an Earthly tailed mammal. The tailbone probably tucks in a bit more.
Admittedly, I've had a couple medical types tell me recently (while
working on my slipped disk), humans aren't really built to sit, either.
Chances are, if you were to encounter a wild human swinging from trees
that had never attempted the seated position for his entire life,
he'd probably groan in pain the first time you forced him to sit in
a chair. Us "civilized" types have gotten used to the spinal twists.
I've heard of similar reactions when adult Austrailian bushmen first
put on shoes, it's _painful_ to them.
Perhaps we can extrapolate a similar effect on Kats- they spend so much
time in chairs, they simply "get used" to having their tail wedged up
in the small of the back, or off to one side, or wherever.