Yeah, this is a non-issue. The safest way to do it is to make them contractors for the two-week period. Nothing looks bad about a two-week consulting contract.

Some trickier issues with trial periods are:

- If they currently have a job, they will typically need to quit the other job before they can do any work for you, even if it is on nights and weekends, and even if it is unpaid. Otherwise there are serious legal issues around IP. So it's no good for poaching.

- A good candidate will have several offers. Even for a two-week trial period, they will probably need to turn down those other offers. That sucks for the candidate because it will really muddy the water with those other companies if in two weeks they want a job again. They could always get offers from other companies, but if the candidate actually wanted to work at those other companies, why didn't she interview there the first time around?

Both of these are surmountable if you are a genuinely desirable employer. For one thing you have the flexibility to talk only to awesome candidates, and awesome candidates are less likely to have problems accepting offers that they previously rejected. (Perhaps even on better terms -- it's very powerful to walk away from a negotiation while you have the upper hand.)

In some countries this information turns up when you do your taxes for the end of the year. And not all job markets are as huge and "anonymous" as the U.S. job market - some (like Israel) are relatively small (a few 10ks of programmers probably) and word gets around. Besides, if you get asked on an interview about what you've done in the recent past in terms of looking for work you're basically lying if you're not mentioning a brief period of employment. Not a huge deal, but still it's not honest and some people would rather not.

Background checks will show where you've worked, unless you were getting paid illegally. Still, I agree with you. It isn't something to scream out loud.

Background checks are being restricted in CA (by laws that became active in Jan '12), but even before that, I doubt it. Background checks are more like credit checks than employment history checks, except they include law enforcement activity.

Background checks are nowhere near that accurate, they usually rely on information you, yourself have put out there, they don't have some sort of direct pipeline to your w2 forms.