Abaddon honey, have you read Damon Knight's story "To Serve Man"? Altruistic aliens come to earth, give us cheap energy and a cure for cancer... why are they so anxious to take care of us? They have a handbook to which they refer regularly. UN translators work feverishly to translate a stolen copy of the book. They finally manage to crack the language enough to get the title of the book... it's 'To Serve Man'. Wow! What altruists!
Aliens offer vacation packages to humans, take them on big ships for intergalactic bonding. Humans swarm to sightsee the universe.
As a group of dignitaries prepare to board ship, a linguist comes tearing across the tarmac, shouting 'NO! No! I've finished the translation! IT'S A COOKBOOK!"
The other scenario is of course found in the fabulous old film 'The Day The Earth Stood Still" with the gorgeous Michael Rennie as Klaatu. Aliens come here to warn us that if we attempt to take our warmongering ways off-planet, the intergalactic robot police force will blow us to oblivion.
I imagine either of these would be more likely than just some species cruising the universe looking to make new friends and share the wealth.
Love,
Mommie
too curmudgeonly to believe in benevolent visitors