We can all spot terrible employees: they under-perform, they don’t work well with teams, they struggle to meet expectations… but oddly enough, it isn’t the obviously terrible employees who cause the real problems.

Whether clearly incompetent or unbelievably lazy, they’re easy to spot. So although it’s never fun to fire people, at least you know there’s a problem–and you can quickly let such employees go and move on.

The real problems are caused by employees who appear to be doing an OK job but meanwhile act like what a friend once called an “insidious cancer,” slowly destroying other employees’ performance, attitude, and morale — and with it, your business.

Here are not so obvious signs an employee is poisoning your company.

1. They thrive on gossip.

Before a meeting, some of us were talking about supervisors in another department when our new boss looked up and said, “Stop. From now on we will never say anything bad about anyone unless they are actually in the room. Period.”

Until then, I never thought of gossip as a part of a company’s culture — gossip just was. We all did it. And it sucked — especially because being the focus of gossip sucked. (And in time, I realized people who gossip suck too.)

If an employee has talked to more than one person about something John is doing, wouldn’t everyone be better off if he stepped up and actually talked to John about it? And if it’s “not his place” to talk to John, it’s definitely not his place to talk about John.

Saying “Did you hear what he did?” is like saying “I have nothing better to do than talk about other people.”

Not only do employees who create a culture of gossip waste time better spent on productive conversations, but they also cause other people to respect their co-workers a little less — and anything that diminishes the dignity or respect of any employee should never be tolerated.

2. They hurry to lead the meeting after the meeting.

You have a meeting. Issues are raised. Concerns are shared. Decisions are made. Everyone in attendance fully supports those decisions. Things are going to happen.

Then someone holds the “meeting after the meeting.” Now she talks about issues she didn’t share earlier with the group. Now he disagrees with the decisions made.

And sometimes these people even say to their teams, “Look, I think this is a terrible idea, but we’ve been told to do it, so I guess we need to give it a shot.”

And now, what was going to happen never will. Waiting until after a meeting to say “I’m not going to support that” is like saying “I’ll agree to anything, but that doesn’t mean I’ll actually do it. I’ll even work against it.”

Those people need to work somewhere else.

3. They say, “That’s not my job.”

The smaller the company, the more important it is that employees think on their feet, adapt quickly to shifting priorities, and do whatever it takes, regardless of role or position, to get things done.

Even if that means a manager has to help load a truck or a machinist needs to clean up a solvent spill; or the accounting staff needs to hit the shop floor to help complete a rush order; or a CEO needs to man a customer service line during a product crisis. (You get the idea.)

Any task an employee is asked to do — as long as it isn’t unethical, immoral, or illegal — is a task that employee should be willing to do, even if it’s “below” his or her current position. (Great employees notice problems and jump in without being asked.)

Saying “It’s not my job” says “I care only about me.” That attitude destroys overall performance because it quickly turns what might have been a cohesive team into a dysfunctional group of individuals.

4. They think they’ve already paid their dues — and they act like it.

An employee did great things last year, last month, or even yesterday. You’re appreciative. You’re grateful.

Still, today is a new day. Dues aren’t paid. Dues get paid. The only real measure of any employee’s value is the tangible contribution he or she makes on a daily basis.

Saying “I’ve paid my dues” is like saying “I no longer need to work as hard.” And suddenly, before you know it, other employees start to feel they’ve earned the right to coast too.

5. They believe experience is an end in itself.

Experience is definitely important, but experience that doesn’t translate into better skills, better performance, and greater achievement is worthless. Experience that just “is” is a waste.

Example: A colleague once said to younger supervisors, “My role is to be a resource.” Great, but then he sat in his office all day waiting for us to come by so he could dispense his pearls of wisdom. Of course, none of us did stop by–we were all busy thinking, “I respect your experience, but I wish your role was to do your job.”

How many years you’ve put in pales in comparison with how many things you’ve done.

Saying “I have more experience” is like saying “I don’t need to justify my decisions or actions.” Experience (or position) should never win an argument. Wisdom, logic, and judgment should always win — regardless of in whom those qualities are found.

6. They use peer pressure to hold others back.

The new employee works hard. She works long hours. She’s hitting targets and exceeding expectations. She rocks. And she eventually hears, from a more “experienced” employee, “You’re working too hard and making the rest of us look bad.”

Where comparisons are concerned, a great employee doesn’t compare herself with others — she compares herself with herself. She wants to “win” that comparison by improving and doing better today than she did yesterday.

Poor employees don’t want to do more; they want others to do less. They don’t want to win. They just want others to make sure they don’t lose.

Saying “You’re working too hard” is like saying “No one should work hard, because I don’t want to work hard.” And pretty soon very few people do — and the ones who keep trying get shunned for a quality you need every employee to possess.

7. They hurry to grab the credit …

OK, maybe he did do nearly all the work. Maybe he did overcome almost every obstacle. Maybe, without him, that high-performance team would have been anything but.

But probably not. Nothing important is ever accomplished alone, even if some people love to act like it.

A good employee and good team player shares the glory. He credits others. He praises. He appreciates. He lets others shine. That’s especially true for an employee in a leadership position — he celebrates the accomplishments of others secure in the knowledge that their success reflects well on him, too.

Saying “I did all the work” or “It was all my idea” is like saying “The world revolves around me, and I need everyone to know it.” And even if other people don’t adopt the same philosophy, they resent having to fight for recognition that is rightfully theirs.

8. … almost as fast as they hurry to throw others under the bus.

A vendor complains. A customer feels shortchanged. A co-worker gets mad. No matter what has happened, it’s someone else’s fault.

Sometimes, whatever the issue and regardless of who is actually at fault, some people step in and take the hit. They willingly accept the criticism or abuse, because they know they can handle it (and they know that maybe the person actually at fault cannot).

Few acts are more selfless than taking the undeserved hit. And few acts better cement a relationship. Few acts are more selfish than saying “It wasn’t me,” especially when, at least in part, it was.

Saying “You’ll have to talk to John” is like saying “We’re not all in this together.” At the best companies, everyone is in it together.

Anyone who isn’t needs to go.