Sam was going through all the information that he gained.
He threw the tracker into the chessboard as he really didn't want to lose such a skilled person. So, he wasn't able to get much information about him. But still, from the other members on par with him, Sam got some information.
His technique is based on something called energy scent and it is only possible because of some constitution of the body. Even though spiritual energy will be purified when it goes into the body based on the cultivation level and technique, it will also be marked by the person. It is the cultivator's energy from that point onwards.
There will be something that is faintly similar to the scent when used. But that scent could not exactly be sensed normally. Only a special constitution like this could make it possible for someone to sense the scent of something like this.
Even though it is called scent it is more like distinguishing between different energies based on the user.