I think they can work. I've talked to one service here in AZ, and my concern is that he gets a lot of success by using his network NATIONALLY, to get kids in front of coaches. I am not sure this guy sees my son at any of the schools he hopes to attend (that's the feeling I get), so I'm not going to pay for his services, even if they are good. If my kid had a wider list of schools he'd like to attend, then it could well be worth the money.
The way I would measure effectiveness is to look at the list of kids they have represented (service in AZ shows their current "clients"), and see if there are kids whose commitments seem to exceed their measurables and stats. That would tell me that the service might do something more for the kid than he could have done himself. I will say that the service in AZ has placed several kids in D1 programs that really, really surprised me. How much "placing" the service did is unknown, but they have surprised me with at least 5 commitments in the past year.
The amount of people with their hands out (showcases, travel coaches, college camps, etc.) to help your kid "be seen" can be overwhelming at times.