Here is a unique one...
Your favorite worker has just saved your behind, now you discover he/she has been bad-mouthing the company on FaceBook and the company president wants ACTION!!!
What do you do?
I'm not really sure how unique this one actually is. People are often both fabulous and seriously damaged in some ways.
People are full of "ands." What I mean is, they can be lazy and productive; maybe being lazy helps them find the best way to be productive, for the amount of productive they want to accomplish (as opposed to the amount of productive they might accomplish if they were less lazy). People can be racist and compassionate. They can be reasonable and irrational.
People are typically not "buts" (at least spelled that way); while a person would probably like to be aggressive but friendly, traditionally "but" negates the word in front of it when we process it in the back of our skull. So even if the statement is true--I, for example, am a control freak but I want everyone to like me--there's a good chance you'll wander off thinking I'm an attention whore more than thinking I need to micromanage stuff. "But" cuts out part of the thought. "And" is inclusive, and lets us know that people can have good traits and bad ones.
As a co-worker or manager, the fact that they have good traits and bad ones is intrinsic and important knowledge. As long as the good activities outweigh the bad ones--for various values of weight and your mileage will vary--they are worth keeping and putting up with. If the bad outweighs the good, and if you can't correct the behavior, you'll spend a lot less time with them and someone may fire them.
And that is a key point: behavior. People are not their behavior. When working with someone, be clear on the difference between the person and the behavior. You cannot change a person; they are who they are and honestly, would you really want to change who you are for work unless you REALLY love your job? But behavior can change. Behavior is a lot easier to change.
In the case my father sites, the person in question is very good at their job, and has done their manager an excellent service AND they've seriously pissed off upper management.
So you talk to upper management. You also talk to Human Resources. Typically, most firms where you work will have an employee handbook or website spelling out what is and is not allowed respective to the company. It will also include the practice by which you redress failures to respect those company rules and regulations.
Most of the time, a person's overall value is weighed against the transgression, and the handbooks/websites/HR policy is written to allow for a first offense without being fired as the immediate result of a transgression. In most states (and you should really check with a local lawyer or your company's HR person), if the handbook indicates a warning is required before firing for most or all behaviors that are forbidden, even if the president of the company is so mad he/she is spitting teeth, your employee will not be fired. You may be heavily recommended to have them clean the bathrooms with their own toothbrush (or some other type of correction), but they'll keep their job.
If this is not their first transgression, however, you have to do some thinking. Can this person be trained out of the bad behavior? How hard will that be to do? Have you already approached them on this (or a similar) topic? What is the value of their work compared to the transgression and the potential of it re-occurring?
In the example given, that person did do some great work. He/she, however, has bad mouthed the company in public on Facebook. A first time offender is a relatively easy answer: whatever HR has prescribed is what you can do; if that prescription involves firing, you can certainly stand up for that person and, if you believe their behavior can be corrected, agree to take that on (and any future bad behavior in this area from them). This will usually preserve that person's job, but involve follow up steps; anything from restricting website access at work to random checks of their pages.
An offender where this is not the first time this behavior has happened (or behavior equally as bad) is messier. In this case, a conversation with the offender is required prior to talking to upper management. You need to discern from the conversation if a) they know what they did was wrong b) they have a plan in place to prevent it from happening again and c) if this is a second or third or close to another "bad" type of offense, what makes this time different than any other. With this information you can decide if this person is worth risking your reputation to preserve in their role. By asking they not be fired, you are in effect, telling upper management you can and will manage the behavior. If you do not or can not, then your reputation will be damaged the next time something happens with this employee. So think carefully.
I am a huge fan in believing in your team. I have a later blog post planned about defending your team, even if you want to kill one member (or all of them). Know that, in defending a teammate, you are making or breaking yourself (a little or a a lot) with the fortunes of the person being defended.
So, in the end, only you