I'd thank them for their advice, but let them know that I prefer to figure things out through experience since opinion is all relative.
Several considerations: As an employer relations specialist, if I learned for a fact, a particular person was spreading gossip about everyone and everything in the office( question states office, coworkers, boss). Obviously the coworker needs to be taken aside and privately told that gossip is not appropriate because it reflects badly on them, as well as demoralizing everyone hearing the gossip. And to STOP, immediately, no more slander. Also, is it just verbal? Or did the coworker print any of their comments on social media? Which amounts to negative advertising, as well as potential libel. Depending on the coworker, it might not just be a negative person saying negative things. If possible, take a look at their situation. Is there something which could be done to improve the office. We are not in a bubble, the public (non-coworkers) can see and hear what we are doing. Majority of the time it is sour grapes.