I didn't meet them personally, but have seen (psychically healthy) people who told me about facing strange phenomenae during their lives. What I believe is that we have lots of affordable and high quality cameras today together with high availability of the Internet and social networks, which mean that facts will be shooted on sight and widespread in an instant. What I admit is that aliens in the most basic life forms such as microorganisms can appear and exist outside of the Earth because here on our planet there are such species that are able to live in extreme conditions, even in the open space. But that's not what you'd like to hear about, don't you? )))