There are no such things as active or passive candidates in the recruitment market, there are only good candidates and the rest. OK, I know that at any one time there are people out there who are actively scouring the market for a new job, and many more who are not. But the point is that this is a candidate perspective, not a recruiter one. Where recruiters can go wrong is in looking for sources of new candidates who are not looking for a new role or may be unavailable to their competitors, i.e 'passive candidates', but can still be delivered to them as if they were 'active'.
I can understand the problem. I worked for an exec-level job board where much of our early growth came from companies looking to us as a different candidate pool. They and all their competitors used the same job boards and came up with the same candidates for the same jobs, for which of course they were all in competition. If we were successful for one agency, it was not long before the competition turned up in force. Good for us, but the same problem for the recruiter.
But looking for active or passive candidates is missing the point. And it's lazy recruiting practice. Recruiters get paid to find the right candidate. Sometimes it will be possible to find the right candidates from a job posting, as at any one time some, but by no means all of the most eligible candidates will be looking to change jobs. But to be consistently identifying the best available candidates means getting of your butt and approaching the people your client would want you to be talking to. You cannot expect a 'passive' candidate to come to you. To find the right candidate you need more than one string to your sourcing bow, and with the wealth of information online there has never been an easier time to do this. Recruiters - get out there and engage!