I've never had any problem printing on any brand of disk using either original Epson or the few aftermarket inks I've tried. I just started on a CIS in my R200, and it's doing fine on everything I've run through it.
I suspect you got a bad batch of Verbs, or a bad batch of ink.
Why are you so opposed to spray-sealing your disks? It's cheap, easy, & effective, and it allows you to get the finish type that you want without paying extra for the disks up front. I use only Patricia Nimock's from Wal-Mart for ~$4/can, and I haven't emptied the first pair of cans yet (1 matte, 1 gloss) on a few hundred disks.