Not sure if you’re asking or making a statement.
But you can “never be sure” of anything on this plane… that’s kind of the point of the material planes. But that’s a much deeper convo for a different day.
You can however:
- Commune with your Higher Self to see if the field is working (pitfall - remembering what was discussed when you come back down into your body/ego)
- Do muscle testing (pitfall - getting false positives out of, again, ego)
- Ask your guides for a clear sign (pitfall - same as above, skewing results based on ego)
- Having faith/use intuition (pitfall - the duality based nature of the ego will create doubts when possible)
- Wait til you die (no real pitfalls
- cause you know that you know, for sure, no kidding, for realsy 
)
Hopefully you see what common denominator is for all the “pitfalls” lol
That said, everything else in life is exactly the same soo… 