Ten good points to know that your visitors are Fakeliens:

From Mr. Bohne:

1. They communicate by Pee-Bursts.
10. They post to UseNet from an
=A0=A0=A0=A0AOL-account. =A0 :-)))

You might add: when queried for specifics, they cannot:
1. Explain the nature of space
2. Describe, much less explain, the cause of gravity
3. Explain the working principle, systems and subsystems of a hyperdrive

...when all this would be kindergarden stuff to any spacefaring race.

oc