[adipginting]

That is a positive assesment. On the other hand, imagine if the aliens think that the senders of these probes were deliberately sending pathogens to the aliens' worlds. This is a statement of war.

[rapind]

They'll just assume that the idiot species sending out statements of war have already been taken care of (probably by themselves).

[spinlock]

The aliens could just send back blueprints for a black hole weapon and wait for us to do the wrong thing.

[euroderf]

... starring Jodie Foster, of course. Screenplay by the evil anti-Sagan.