Crazy that people do this kind of crap. I've reported a number of them already, my successful report % doesn't seem to be going up though which is weird.
Your percentage will only change when a mod reviews your report and either marks it with a yes or no. It's not instant, but if you reported a bunch of those spam posts in the last 15 minutes or so expect your percentage to change in the next couple of hours as mods review the reports.