The guy I bought my gray Missouri Fox Trotter from had no concept of gray. She had a previous foal, whom I wanted to meet and didn't get a chance to, that he claimed was blue roan. But I am 99.9% certain he was a gray because his momma is a gray (50% chance of getting gray there) and his sire was the same sire as my mare's current baby, and the sire is chestnut.
I am fairly certain you can't get blue roan from a chestnut stud and a black-based gray.....right? Not only that, but when he saw more recent photos of my mare he said something like "I thought she was darker than that." Um, well, she IS going gray so she looses more color every year!
So yeah, that doesn't surprise me at all. A lot of people can't seem to tell roan from gray.
What might be confusing is that true roans DO change shades with the seasons.....they can change from light to dark quite a bit depending on the length of their hair. But they always keep a dark head. That is the telling factor for me with a "true" roan.
Then you have varnish roans (Appaloosas) which I am not experience with so I will not comment on them.
Then you have sabino roans as well. They won't have the dark head of a "true" roan but will have sabino markings. To me, those are easier to confuse with gray than a true roan.
So yeah, I guess it can get a big confusing, but I always look at the head and the tail. Is the head dark and the rest of the body roan? True roan. Is the head and tail roaning also? If so, either sabino or gray. Does the horse have extensive white markings? If so, sabino.
But one pattern doesn't necessarily exclude the other, so you could potentially have a true roan going gray, or a sabino going gray. That would be a bit confusing.
But like this guy for instance, is sabino, but I could see how someone might confuse him for gray....the face and tail have white hair outside the white markings.
Now do sabinos get lighter with age???
A lot of true roans DO look very similar to the early stages of gray. I have met a couple that look a lot like my 3 yr old going gray, except that my 3 yr old has white in his tail and white on his face. Other than that, they looked very very similar.
So yeah, I look at the head and tail to distinguish.
Now don't even get me started on grulla! Most of the people I have met who say the have a grulla do NOT have a grulla. Usually the horse is sooty buckskin or even sooty palomino.