Do you believe aliens have been to earth?
We will never know whether there are intelligent beings out there, because, if they are, in fact, "intelligent", no chance they will come to this crappy planet.
"Do you believe aliens have been to earth?"
Instead of "believe" rephrase to "Do you think aliens have been to earth" -
ANSWER: No I don't think so
Believe it or not, you can "believe" anything you like without any evidence, whereas thinking requires intellect