Re: Extraterrestrials haven't visited the Earth yet because:

[Ratazong]

But there is plenty of evidence that aliens already visited earth:

• many UFOs have been sighted in the last 3500 years
• some ancient buildings have been created by them
• they abducted many people (wikipedia rates 11 cases in the last 50 years as notable)
• in fact they abducted so many people that smart people buy an insurance against alien abduction
• actually, some people are considered to be extraterrestians
• there is even an Alien-namespace in CPAN (even if it seems to be misused for mundane modules...)

So the basic assumption of your poll looks wrong to me. Maybe it is just a desinformation-campaign of the Illuminati?! Then we will probably never know...

So long, Rata (resuming his studies of the Principia Discordia in search for the secret tunnels to Atlantis)

[Jenda]

Smart people SELL insurance against alien abduction.

[Ratazong]

Here is a Dilbert on a similar topic.

[Erez]

there is plenty of evidence that aliens already visited earth

XKCD: Settled

[morgon]

I don't worry too much about the abductions as such but I fear their the anal probes.

[Anonymous Monk]

But there is plenty of evidence that aliens already visited earth: many UFOs have been sighted in the last 3500 years

:) I believe in UFO, I believe I can see things flying, and I don't know what they are -- that don't mean its aliens, it doesn't follow