I often obsess about how someone might dislike me or think negatively of me. Sometimes, I can confirm that it's true when I encounter the same person with the same reaction again. However, sometimes I'm being paranoid in situations like for example, a student whom I thought hates me and gives me bad evaluations suddenly thanks me and says they actually like my lessons.
When it comes to dating though, I trust my instincts. If I think a guy has bad intentions, then he usually has. It really depends on the situation. Now, I'm not sure how big the connection is between self-preservation instincts and paranoia.