My dogs 'talk' to me all the time and my job relies on my ability to 'hear' other peoples dogs talking to them and me.
Sadly I firmly believe far fewer people would own dogs if they really understood how their dogs were feeling and what they were thinking - the dogs that are in pain, who are fearful, anxious, or who live to kill stuff... I don't think people would like it at all.
Some people have some very stupid ideas about what dogs are capable of though!
Some examples - my friends dog is super smart...
She's great at spatial awareness and problem solving - I've seen her realise an object wont permit her to jump through a gap if its in her mouth, put the object down, hop through the gap, lean back through and pick the object up and wiggle it through in a position where thats now possible...
And she will make herself comfy... if her person is in the bath, and she wants to be in the room, but theres a hard floor in there - she'll go get her dog bed, bring it through to the bathroom and lie on it.
Not all dogs are capable of that - none of mine are - but mine tells me when my blood sugar is too high or low, he also offers DPT when I have muscle spasms, which isn't something I've trained for.
Another of mine, now very elderly, can plot a route to get to the object he wants, even where the route in question takes him AWAY from the object, putting his goal out of sight initially - this is something lots of animals struggle with and honestly a lot of humans would when young.
Another friends dog will use tools - she will grab a chair and drag it across a room to stand on it to get on the work top to steal food!
Some of my past dogs have learned abstract concepts like biggest, smallest, middle, up/down/centre, left of/right of etc.
One went so far as to be able to do this with not just identical objects or the training set up, but do it in the real world, anywhere, and with non-identical objects. So he could bring you the biggest of the three objects, if one was a tin of beans, one a tennis ball and one a teaspoon. Most dogs who figure out abstracts need to work with identical stuff so three tins or three balls etc, and will struggle outside of a training environment.
Last night I watched my generally 'not that bright' hound get up from one dog bed, look at our saluki in the comfiest bed, and start to flirt with her, telling her he'd like to play. When he flirts he is ridic, its all waggy tails and tiny little dancing steps which on a hefty hairy hound looks comical... and Miss Saluki finds it irresistable...
So she got up to play, he play bowed at her, did one lap and straight into the spot she'd vacated which is what he wanted all along, leaving her confused and bamboozled (and in need of a cuddle, which she got from me, bless her dimwitted heart(.