The obvious answer, of course, is that you shouldn't, especially if you're in contact with people (as most jobs require). As a manager for many years, I plead guilty - and I'm certainly not alone. Chicago small business owner Jay Goltz says that going to work sick is irresponsible and potentially hazardous to those you come into contact with. The problem is that for the people who don't get sick days, staying home takes a bite out of your paycheck. From the NYT's You're the Boss blog:

Now, let's talk about the proposed solution: mandatory sick pay. First of all, while many business owners are quite worried about this idea, it won't necessarily have the negative impact they fear. If a company doesn't offer any paid time off (which I would have a hard time defending), it will indeed have a new expense. But if a company already gives vacation time, which most companies do (including mine), it can simply change to a new system and offer a number of "paid time off" days. These days would be for anything: vacation, sickness, sick kids, flooded basements and visits from your mother-in-law. That may be a better way to handle this anyway.

It's definitely a step in the right direction, but work life is never that neat and tidy. There will always be a report that's due in two days or an extra-busy week at the store, or a boss who is already annoyed that you took two days off the week before. And of course, you always try convincing yourself that you're not contagious, as if some magic cone is separating you from everybody else.

Small businesses are already paying the price for poor banking oversight, higher real estate taxes, higher unemployment taxes, out-of-control health insurance and frivolous lawsuits. Yes, business owners have responsibilities to their employees and society. But is it really hard to imagine why many are reluctant to hire new employees? If we are to have an intelligent, productive, fair discussion on this topic -- and I look forward to seeing one in the comments below -- we have to stop portraying employees as victims and businesses as the bad guys. It's not as simple as, say, staying home when you are sick.