Siddhis: This is a term for spiritual powers of various sorts, from psychic ability to being able to levitate, to be present at various places at once, to become as small as an atom, to materialize objects, to have access to memories from past lives, and more.
Miraculous events may occur around certain apparent enlightened ones or apparent gurus. Keep in mind that these occurrences are not personal and not caused by the so-called enlightened one. These are impersonal events not directly caused by the apparent being.
Who would want to follow a so-called wise person who depended on slight-of-hand and parlor tricks to attract followers? This is more the sign of a low level charlatan than a guru.
The true wise man would probably prefer not to have crowds of followers. He may have to deal with groups of seekers because he wishes to help, but he certainly wouldn't be performing circus tricks as a means to attract followers or show his power.
True power does not need parlor tricks to attract a crowd. In fact, the true wise men would eschew such theatrics. If a miraculous event does occur, the truly wise man would certainly disclaim any personal cause. The true guru knows that it is not his power, a personal power, that would cause such an occurrence.
It's a sad scene when a true seeker gets caught up with a circus performer of siddhis. Years can be wasted. If your are attracted to someone because they can produce ash, make trinkets appear, or produce perfume, you might be due for a good look inside yourself. What is your motive in this? An honest evaluation might allow you to see that you are looking for power, not truth.
If you are attracted to displays of siddhis, card tricks, etc, you are watching a sideshow. You are actually delaying finding the truth. Goethe's Faust was the story of man who sold his soul to the devil for power. Don't sell your soul to a man who entertains you with slight-of hand, and the manifestation of trinkets. Fools gold!
Truth is not an object. It doesn't need magic displays to make itself known. It is far more subtle than that, and far closer to you than your guru.
The true teacher doesn't need you. Jack Kornfield said that the amazing thing about Nisargadatta was that "He wanted nothing from me." The real teacher does not need to self promote. He will be known by what he has become. His teaching is enough.