It's easy to recognize others. Just look at a person's Energy Signature.
Every being openly displays its Energy Signature. That's nothing esoteric, but a kind of impartial mental and emotional passport. Everyone perceives it all the time, though presently few people are aware of this.
The signature manifests e.g. as that initial feeling when you meet someone the very first time. This brief flash of feeling makes you intuitively aware whether this person will be enjoyable or boring, inspiring or irrelevant, or if he or she inevitably will cause trouble for you later.
When falling in love, the other's energy signature alerts you to the intense emotions that lie ahead.
The higher the level you focus on, the clearer you perceive the (inner) state of the being before you, - the energy at his disposal, - the intensity and drive with which he makes his dreams come true, or the lethargy with which he clings to stagnant situations, - his willingness to learn and to expand beyond his present limits, - his deepest intentions, - his life's potential, - and so much more.
The energy signature is a snapshot of everything a person IS NOW and thus also of everything he or she ever manifested in the past.
And you can see it in the face as well - no amount of cosmetics will ever conceal this inner core; - it also shows in their bearing, - what words they select, - the manner of their movements, - and even in their smell.
The deeper you dare to explore this plain, open information, the more precise impressions you get, and the easier you'll recognize who shows the spark.
Never expect to find perfect, accomplished beings when looking for others. Most probably you'll only see a promise, a potential, a glimmer hidden behind the conditions they live in.
Respond to this inner potential, ignite their fire, make them aware of their own inner strength, confirm their subtle insights, - show them that they are not alone, that there are others, - help them expand.