What is a phrase/word to describe someone who is oblivious to the bad in people
I think 2 options are gullible and naive:
naive
- having or showing unaffected simplicity of nature or absence of artificiality; unsophisticated; ingenuous.
- having or showing a lack of experience, judgment, or information; credulous: She's so naive she believes everything she reads. He has a very naive attitude toward politics.
gullible
easily deceived or cheated.
- Stop looking at the world so naively/gullibly!
- Stop being so naive/gullible of the world!
The best single word suited to this would be naïve.
You could also use the phrase "bleeding heart" but A) you'd need to change the construction of your sentences, and B) it could come across a lot harsher than you intend.