As this is the age of cheaters and cheated, it is not difficult to find a cheater. Cheating is one of the tendencies of the conditioned soul and to be cheated is a common experience of everybody.
How do we recognize a cheater? With the highten academic education every fool can enjoy today, his trickery is becoming more sophisticated. Nevertheless, some things remain the same.
A cheater will likely present himself as "the victim of the circumstances", never accepting to be the cause of his mischief. It doesn't matter if it is a man trying to seduce a woman or a woman trying to seduce a man, or a penniless fellow trying to "borrow" some money. They are all "victims of the circumstances", the needy ones who try to provoke compassion and mercy.
One should be aware of such "victims".
When it comes to spiritual life, things get much worse. Afterall, a materialist is either falsely offering higher sense gratification, or seeking higher level of sense gratification. The result can be tasted or felt physically. If the promised state of wellbeing is not reached, one realizes one got cheated.
A pseudo spiritualist is far more dangerous. When concocting his own path, he still can be easily identified. But when using authorized scriptures for unauthorized purposes, he is truly a venomous snake who can make by his touch even milk poisonous. However, when challenged to back up his teachings with action, he will respond in the same way other cheaters do - he will declare himself to be the victim of the circumstances and, here comes another symptom of a cheater, he will point to the future. In the future his promises come true, it just takes a little investment from our side..into his pocket:-)
As defined in Bhagavad-gita, charity given without any verification to an unworthy person is a charity in mode of ignorance. Energy invested into material cause will produce material result only, which is mostly of destructive nature.
One should not be fooled by a cheater in name of spiritual life, however good looking he may be.
How to protect oneself from such cheaters? One should be informed, demand transparency and personal response, and contact those who dealt with such a man before. (Or woman, to be correct in modern terms:-)