You can see "Police" on the doors when it is DIRECTLY BEHIND YOU??? Really?The ones that say poleece on the doors of course. Gee, everybody knows that.
The answer is that you cant. So an unmarked car with a ton of lights looks much like a marked car with a ton of lights in the rear view mirror of the violator getting pulled over.
For years, this whole topic has been one of sour grapes by people who don't like police enforcing traffic laws on them.
I don't know af any remote rural areas that have unmarked traffic enforcement vehicles. It is usually in more populated areas. HIGHLY unlikely that someone is going to spend $3k-$5k in lights for their fairly new look alike patrol vehicle to impersonate a cop in a city full of real cops.
Use common sense, drive to an area that is well lit/populated. You will be ok.