"a vague vision" is grammatically correct and can be used in written English.
It refers to a hazy or unclear mental image or idea. Example: As she closed her eyes, she caught a glimpse of a vague vision, a memory from her childhood that she couldn't quite recall.
AMY DAVIDSON: Rob, or a vague vision but no plan at all.
A vague vision (e.g., "providing information to anyone, anytime, anywhere") can mean millions wasted on chasing elusive benefits.
It was just a case of having a vague vision — which I couldn't define, obviously, until the music was made".
At the time, the Nets were languishing in Newark and could sell only a vague vision of Brooklyn and an under-construction arena.
If Bannon has an actual plan or even a vague vision for a health-care alternative to the Ryanism that he supposedly disdains, we haven't seen it.
Initiations tend to promote a vague vision of Pan-Asian identity that reflects the history of Asian-American scholarship and activism, but whose urgency has been hollowed out by years of apathy.
In duelling ads released for the second round, Hollande depicted a pleasantly vague vision of an equitable, unified France, while Sarkozy focussed entirely, obsessively on immigration.
Utterly ignoring his two prospective Democratic opponents in the race for governor, Gov. George E. Pataki embraced the unanimous support of the New York State Republican Party in his bid for a third term yesterday, setting out a sunny if vague vision of where he wanted to take his state should he win re-election this November.
This ad is just 30 seconds of Mr. Romney laying out a rosy, albeit vague, vision of what the country would look like under his leadership.
The Florida senator tried to pivot away from talking about "the challenges we're facing" and instead present an optimistic, albeit vague vision for the United States.
Thus, the pro-independence lobby was able to campaign both positively and over such a long period that it had time to articulate its (hitherto vague) vision like never before.
