Whenever someone is said to have a good reputation, some relevant questions are "For what?" and "In which circles?"
I've known individuals whose peers thought they were manipulative or lazy but upper management had them tagged as extraordinary performers. [They were, but only when it came to impressing upper management.] Conversely, their competitors may have secured the trust and respect of peers but were little known by the folks who would make promotion decisions.
Aside from knowing how your own reputation fares at various levels, you are wise to know the people who know; the ones who will give you blunt but accurate assessments of the knowledge, skills, and abilities of Tom, Dick, and Maria. That information is invaluable when assembling teams or allies.
Eventually, your knowledge of who's real, who's improving and who's fake or dangerous should approach that person's. At the back of your mind should be the equivalent of George Marshall's little black book in which he assessed the caliber of officers he'd met in his career. [Hmm. Patton is good for this and Eisenhower is good for that.]
Trust me. It will come in handy.