[jacquesm]

And that they didn't bother to compress to save on bandwidth.

To me that's the kicker. There's only a 100 year or so window during which you can catch a civilization's transmissions un-encrypted and un-compressed. After that it might as well be noise.

[tzs]

Even after they have switched to encrypting and compressing their transmissions, they might still have have unencrypted, uncompressed station identification messages transmitted periodically.