W.r.t to LGMs (little green men): if they have the technology to come here, they are more than enough capable of either:
1) hiding perfectly (so no sightins) or...
2) crush us without the least difficulty (so no need of playing hide and seek)...
...so forget about LGMs.
I think the 99% of the times it is hoaxes/misinterpretation of natural phenomena/too much of substances like alcohol or meths. In the remaining 1% of the cases, black military projects, often performed in the total ignorance of the political leadership.
Bye!!!