There's no foolproof way AFAIK
- and no real value in establishing it one way or the other as far as I can see.
If you are looking for a specific tone or effect you can try both and see which works. The opposite to the original may work best for you!
With effects and processing that you'll encounter in most live and recorded situations the precise tone hunt seems unproductive. Getting the best out of equipment you know well is time spent better IMO.