GS Scorchers are my go to rain tire. I've never had a single slip in many years. I just did an unintended wet/pavement/mud/dirt/gravel tour with my 406 Scorchers and I was impressed with how much traction I got on all surfaces. They rocked. I've also never had any issue getting them mounted evenly.
It's like you got some tires incorrectly marked as Scorchers!! Maybe you got a bunk set...?
I'm basing my observations on 4 different sets of Scorchers I personally have bought as well as reports for a number of other Scorcher-itos who have dropped me a line on my blog.
How much do you weigh? What pressure were you running them at front and rear?