The scary part is, they can do so on a different level than your average human. Pouring over larger sets of data quickly, than you or I have time to consume in our entire lives.
The largest issue, however, is that an AI can find and shed light on dislikable realities of the world.
Racism, sexism, culturism, opposing political opinions... Perspectives that are not "PC" still exist and permeate the digital world along with the physical one. Creating unbiased data is, imo, impossible, as I am also biased, and so are you. I don't know what unbiased data is.
I can certainly say that I have held racist, sexist, religious, and political views at various stages of my life - based on small sample set data, and biased trainers. I have grown a better understanding and no longer hold many of the naive beliefs that I held when I was younger, and will continue to realize how ignorant I am as I live.
The same process will probably happen for any AI.