Not knowing what jobs you are being notified of, that would be really hard to say. The point was made in a post on Volition by a scheduler that SS sweeps his posts on the MSPA job boards and sends those out to shoppers. While there was a note in an earlier post here by a scheduler that they look for shoppers at SS, it is hard to know if that is the exception or the rule.
Here is what I think it all boils down to . . . Obviously you have signed up with a number of companies through your association with SS (if you haven't, there are free lists of legitimate MS companies on this board and others). Are you getting emails directly from these companies? Do you have access to their job boards on their own websites? That is really what you need.
I have never paid to shop and do not intend to do so in the future. Between fairly regular checks of the job boards of companies I have learned shop my area (through experience with them) and occasional checks of job boards of companies who thus far have had few if any shops in my area, my job sheet for November is already reasonably full. In fact I have jobs already scheduled that take me 3/4 of the way to my monthly 'goal' and today is only November 3rd. These aren't just junk jobs gotten by taking everything available off the job boards, the average value of the jobs is currently $21.71.