Not caring about formatting also signals to me that:

- they have probably never worked on a codebase where files are edited by more than 1 person

- they have never done any significant amount of merging between branches

- they have never maintained a large codebase

- they have never had to refactor a large codebase

- they don't use diff/comparison tools to read the history of their codebase

- they have never written any tooling for their codebase

- they are not good team-players and/or only care about their own stuff