Disclosing Spiritual Experiences

I've read that the Dalai Lama tends not to disclose his own spiritual experiences. Is it bad to disclose meditative or spiritual experiences as visions and such? Is there a difference between monks and lay practitioners in this respect? Again for monks and lay holders: what occurs if someone is lying or inauthentic about a spiritual experience? Also, how does one know if a spiritual experience is a genuine one? Thank you