Comparing a few (not "lots of" as you claim) specialists scattered around societies around the world is not a good representation of civilizations around the universe (or at least, we can't assume it to be).
As human as it is, most exploration has been grounded in financial and egotistical needs, not scientific exploration. Maybe the civilization is just as curious as we would be and thus would come for selfless reasons, but that's a pretty big assumption.
Your examples involve creatures that we already know about and have interacted with and "integrated" into our lives (one way or another).
But I suppose the counter-example is "it depends who finds us" -- if it's an intergalactic scientific exploration team of aliens, they'll probably be as nice as can be. If it's an intergalactic mining company, maybe not so much.
The equivalent here would be the contrast between a scientific expedition to explore new species in the Amazon Rainforest (i.e. people who would be benign and take an interest in new species) vs. a bulldozing crew out to find more land in those same rainforests ("Oh look, a bird. Ok boys chop down that tree").