At a minimum, a "well-trained" dog ought to be able to pass a CGC. MINIMUM. That doesn't necessarily mean they have to have been tested for the CGC, just that if they were to be tested, they'd pass. I'd like to see something closer to a heel than the CGC requires (though it doesn't need to be competition-level heeling by any means). Also a longer stay, and there were some other things I was going to add but they just slipped my mind
Maybe i'll remember in the morning.
I consider my dog to be "well-trained." He has passed his CGC after I had him for 8 1/2 months. To be fair, he was probably ready before that, but I thought the test included much more than it actually did, and so I worked longer at it (I had parts of the ADI PAT and the CGC mixed up lol). When I realized that the CGC really didn't cover that much stuff, I had him tested within a month (they're generally held every 3 or 4 months here). He passed his first time. My dog knows the following commands (and I know I'm probably forgetting some):
sit*
stay*
down*
drop* (emergency down)
side/heel
allons-y* (my word for loose-leash walking, as opposed to heel)
wait*
hup (jump over a jump)
starting on directionals (he's pretty solid if I point in a direction)
automatic sit
come*
front
finish (comes to my left, turns, and sits)
lights off
go home (leads me home...not as solid as it was before we moved)
go on (go ahead of me)
starting weaves
starting to retrieve
fix it (untangle himself if he gets a foot over the leash)
wave
shake/paw
roll over (not solid yet, we work on this in between training other stuff)
leave it*
look* (or eye contact/pay attention, with or without a command)
kennel
off*
forward (go forward and apply pressure to a harness...at one point I was working on some guide work with him for shits and giggles and also just for experience; he's far from trained in guide work, but he does know forward and to pull when in harness..I may use that base for driving later)
He also has manners, and will allow me (or other people) to brush him, brush his teeth, scrape/scale his teeth, bathe him, clean his ears, clip/file his nails, examine him, etc. He does not nuisance bark, he doesn't chew things, he doesn't jump on people (he will occasionally paw at me/jump on me if we're doing something wild while clicker training, such as working on agility stuff). He doesn't beg or steal food.
I would not expect a dog advertised as "well trained" to be able to do the entire list I made (I put a * by the ones I think are needed at a minimum), and I would not personally require all those before I call a dog well-trained. I would, however, require all the manners I listed (with the exception of scaling teeth), as those are things that are really necessary to make your dog pleasant to work with. If a dog knows commands but has squat for manners, I wouldn't call it well trained.
I also believe that no dog is ever fully trained; even the most well-trained service dogs (and I've heard of some that know hundreds of commands) can always learn something new. It keeps them mentally stimulated to continuously learn new commands.
As a side note, "fix it" is above all my favorite "trick." It's wonderful to not have to untangle your dog all the time
I highly recommend teaching it to your dog.
Anyway, I do think well-trained ought to mean trained beyond the basics, or at least that the basics are solid and the dog has manners.
ETA: Of course housebroken too! And though I'd like to see a dog that's crate-trained, not all people crate their dogs, and I respect that choice. I don't agree with it, but I respect it.