If a race of beings is capable of traveling the great distance on space in a reasonable time frame:
1) Its absurd to think it hasn't already been studying us at a molecular level.
2) Its absurd to think it wouldn't have created a virus that would greatly wipe us out without them putting one "foot" on the ground.
3) This is all with the assumption that they intend to do harm and are not simply explorers.
I tend to think we would have already been wiped out by aliens if it weren't for other aliens who potentially saved us from them.
i.e. I believe that just as there are good and bad people, leaders, governments, etc... there are good and bad advanced alien species.
The good hopefully outweigh the bad.. as is typically the case in any society, and these good groups have worked their might to let us and other lesser advanced people's be on our own without much interference.







