Though not typically aggressive to humans, attacks can occur for several reasons: illness, hormonal changes related to breeding, and human desensitization. Like most animals, sea lion mouths contain numerous flora and bites are at risk for polymicrobial infections.
Aww… What is human desensitization?
To desensitize someone to things such as pain, anxiety, or other people’s suffering, means to cause them to react less strongly to them.