[Mobhack]

There is no magic flag that you can look at to see if the attempt worked or not. Real troops dont have this, nor do you. But if the enemy fire on you in thier turn, or if you move then it probably did not work (or a fresh spotting roll by the opponent unmasked you again).

Basically - the further away you are then the more chance of it working. Chances at 50m are rather unlikely, 1000m more probable. The smaller your unit size is helps, as does experience, being in cover etc.

You could also try taking cover several times, if you are paranoid and have the spare MP..