Search for ET Probes

Even if ET have never sent a probe to our solar system,
they may have sent fast moving probes to other stars
and systems and those probes could have since drifted
into our system. The challenge is how do you find an
alien probe that's been inactive for perhaps eons?
Especially since we have no clue what such a probe
should look like either when it was launched or after
it has been pelted by meteorites for eons.

I think one relatively easy way to search for these
hypothetical probes would be to use a combination of
radar, lasers and visual spectrum telescopes. If
a probe has a large radio dish then when it is in
a certain orientation to earth (say within 40 degrees
of pointing at earth) it's radar signature will be
louder than that of many random shapes the same
size. Visual observation can be used to determine
the size (a guess can be made). A similar principal
can be used if the hypothetical probe has optics
for sending messages by laser. A powerful laser beam
sent from earth will be reflected more strongly from
the optics of a probe when the probe is in a certain
alignment - although obviously the return signal will
be relatively weak.

These search methods can be tested on known probes
that were launched from earth.

If it's a valid method for finding our own probes
then it might be useful in finding ETI probes under
the usual assumption that ET's communication technology
is similar to our own (or was when one or more of
their probes was launched).

Opinions?

-McDaniel