I'm not sure exactly what you mean by scanning secondary users as you can't directly communicate with a winmx client on secondary. However if you mean when Lagerlout was wondering why I was requesting primary nodes from his cache server more often that needed it was explained to him that it was due to an old application (circa 2009) that was requesting primaries from his cache server on the secondary ports (where this "secondary scanning" logic must come from).
That piece of crap app was simply left open in a vm and forgotten about and that was dealt with appropriately.
I make almost all of my WinMX applications to be completely cache server independent, and the only ones that do use them are these crap apps from way back when that were written vb.net (cringe).