By Shoshana Rosa
In the first chapter of his book on shmirat haloshon (guarding one's speech), the Chofetz Chaim discusses the need for one to surround himself with people who speak positively. According to the Torah, one is forbidden to speak or relate loshon hara through speech and body language (this includes things like a twitch of the nose, a tweak of the eyebrow or the crook of a finger). Letter writing is also an issue.
If a person makes a daily habit of speaking or relating loshon hara, one can assume that s/he is likely to randomly burst into a bout of negative speech. Also, if there is drama going on, such as an argument between two friends, the habitual loshon hara speaker is usually the one egging them on instead of pouring earth on the fire. Rather than smooth down ruffled feathers, s/he may jump into the debate or, worse, she may relay what happened to another person, along with her personal take on events. That being said, hanging out with people who vomit negativity is a little like spending time with powder kegs -- you never know when they're going to explode and spread debris.
Regarding the listeners of loshon hara (remember, the transgression of speaking loshon hara also applies to the listener) bear in mind that anyone who spouts negativity on a daily basis is almost always guaranteed to speak loshon hara to anyone who's willing to listen. "Did you hear what happened to Surie? I didn't catch the whole story, I was making coffee in the kitchenette, but I heard shouting voices in the manager's office and she left the salon in tears." That little line is going to do one or more of the following: cause Surie's co-workers to gossip about her and/or the administration at the workplace. This may result in besmirching Surie's name (at least, among her co-workers) or spreading a pall of ill feeling in the workplace. The Chofez Chaim's best piece of advice regarding negative speakers? Try to avoid conversing with them.
Unfortunately, there are people who persist on seeing life like it's a half empty glass. Although, to be fair, there are those incurably optimistic types as well. These two kinds of views are usually impossible to miss; you'll always be running into one of them at some point or another. Just look at the two friends rushing to catch their bus to work. As it pulls away, leaving them breathless at the curb, one starts to spout abuse at the city's transportation while the second says, "Wow, I guess the bus lines are really on their game today." Who would you rather make a coffee date with?