I can make a very worst case scenario, with apologies to John Scalzi and James Cameron:
[SCENE OPENS]
Alien X walks down the gangplank. It has been a long journey and its tentacles are sore. It approaches the Captain and briskly salutes.
“Captain, we have arrived at the blue planet, I am transmitting the report you requested to your BrainPal now.”
The Captain blinks its three sets of eyes slowly as it absorbs the full analysis of the planet, covering all cultures, species, flora and fauna current and historical to the dawn of time. It takes it approximately two seconds to issue his command:
“I say we nuke the entire planet from orbit. It’s the only way to be sure.”
[FADE TO BLACK]