I do my best to make sure all the job opportunities I post are legitimate and that the companies are in the process of hiring. Occasionally, though, a company will place a link on their employment page, indicating they are hiring again, only to be flooded with applicants and promptly pull the link or put up a notice that they are "no longer hiring at this time."
This can happen within the course of a 12-hour day. In the morning, they may be hiring. By afternoon, they've shut it down due to huge response. This happens when word gets out on a work at home message board or other site. All I can do is post them when I see them and hope you guys get there before the jobs are filled.
Sometimes a person will find a post of mine through search. If it's an older post, the page that's linked to may be gone, or the company was hiring at the time of the post, but is no longer.
At any rate, I've had more positive than negative feedback. So I'll just keep trucking along, posting job opps as soon as I hear about them. I love to hear that someone has found a work at home job by visiting my site. ;)