If you see a "blinkers on" firster, that horse probably cannot run as well or fast as the connections hoped it would. Why? Because the trainer is concerned that they have not seen nearly enough of what they expect out of the horse. And often times, that is because the horse just can't run to their bloodlines. That goes for most trainers in general. Blinkers "on" is trying to make the horse wake up. If you are having to try and wake up a firster, chances are you as a trainer are worried about the level of ability.
An exception would be if you see a horse with a see through bubble on one eye and probably nothing on the other eye. That is a protective lens to help a horse that has injured it's eye either temporarily or permanently.
That is not the same thing and is pretty rare but we do see it from time to time.
There are some exceptions to every rule but all in all, Maggie is right.