What is your experience?
I wonder about the 'can not be homed with cats' used by many rescues, sometimes.
Since childhood, I haven't had a dog (including pups, rescues and strays) which couldn't be socialised to accept it's own cats (obviously the cats play a part in this training!). i.e. 'This cat is family. We don't eat family.' Still, I wouldn't necessarily trust them at all unsupervised with unfamiliar cats.
A friends dog would 'red mist' and attack other dogs and anything smaller than her if given half a chance but even she was socialised to accept her neighbour's cat.
My dogs have been rehomed to me, with kit-cats but I couldn't say they are 'cat friendly'. They'll share water and feed bowls and beds with their own felines (they even clean each other!) but a cat who hasn't been gradually and properly introduced quite possibly wouldn't fare well with them at all.
(n.b. I do understand that some dogs can not be homed with cats! It just seems that this line is trotted out more often than it is possible to be true.)
What's your experience of feline/canine siblings?