Can grown cats who's never seen a dog before, learn to be OK with one?

Occasionally, some cats actually develop a rapport with certain dogs. I had a cat that would perch on the dogs back and go to sleep. My neighbor has a similar pair.

In my experience, however, most cats do not like dogs. Some are merely indefferent, and some hiss, act fearfull, or even attact the dog.

A lot of it depends on the dogs reaction to the cat. A laid back dog would be best. A high prey drive dog is not a good companion for a cat.

I've had tons of fosters come here who have never seen a dog, never mind lived with one. And although most of them never develop a love for Molly [8|] they co-exist pretty well with her.
And they've all been adults.
Check out Tally's Basic Cat Care site she has TONS of info there regarding introducing various pets to existing pets. Good stuff.
I have to keep fosters isolated for up to 10 days then I let them start to meet my pets, including Molly, with a baby gate up to the door (my computer is in the foster room so when I come in here I keep the baby gate up so I can supervise). I always make Molly lay down when she meets a foster for the first time. I think it's less intimidating for the cat to see a big dog laying down.
You want to get a dog who has cat experience. When we were looking for another dog (before Glenda offered to let us have one of her fosters) the first thing I looked for was whether they could live with cats or not. Having 4 of my own, and fostering, I NEEDED to have a dog who could live with cats. I saw some beautiful GSDs in shelters and rescues who were clearly marked "no cats" and as tempted as I was I had to pass.
Luckily Glenda raised Molly with cats so it wasn't an issue.

I have a dog and 3 cats, we had two cats when we got our pup, she was a baby when we got her, the  cats and she get on pretty well, they are kind of indifferent with her, but no problems.

They will likely co-exist and may even be close in some ways.  My adult cats were not thrilled when we adopted one and then a second puppy, but recently, the most hesitant cat has actually been seen head butting and rubbing up against the dogs.

This has been my experience as well.  Adult cats who don't know what a dog is tend to be cautious but basically indifferent.  They will give the dog a punch for getting too friendly and invading their space, and so far the dogs have learned almost instantly to respect the cats.  My only issue has come from rehabilitated ferals who were taught by mommy outside that Dogs Are Bad And Want To Eat You.  If you adopt an adult cat from a shelter check carefully into their background, as usual.

Maxwell was 8 years old when I got otto, they are best buds, they sleep together and play, it hasn't been an issue at all (except otto trying to snack on the cat poo )

I have three dogs and one cat. The cat adores the dogs and vice versa. As for the prey drive, I have two herders and a min. pin and theres the occassional chase, but thats it.

My cats were two when we got Wrigley as a puppy.  One of my cats would stay in the room with the dog as long as she was up higher.  My male cat hid under the bed for about 48 hours.  I was very nervous at first and worried about my cat.  Within a few months, the cats were letting the puppy chase and play (on their terms of course).  Wrigley was even licking the male cats ears.  Although they aren't cuddle buddies, they like each other and they're fun to watch together.

My mom has always had at least 5 - 8 cats in her house and all of them have more or less excepted any dog that have come into the house. The trick is to introduce them slowly like bring the dog in in a crate and let your kittys sniff and see that this dog is no threat there maybe some hot breath at first but they will eventualy get over it. Just be sure to test the personality of the dog you get to make sure it will get along with cats too.