Can you the paint the bottom of a ski. If so, what kind of paint? How to prep?
My advice would be not to touch the bottom of your ski. I think the manufacturer has probably figured out the best way for the bottom of your ski to work and messing with it will effect how it rides.
At least some Goode skis were released with a factory-painted bottom, and they sell (or used to sell) repair paint for the do-it-your-selfers.
Historically, Goode skis have performed pretty well, so you might be able to apply what they used without harming your ski's performance... or not.
I'd try asking them at http://www.goode.com
TW
A good quality Black Satin paint works just fine on Goode Skis.
Goode uses SEM satin bumper black. You can buy cans of it at your local auto parts store.
I skied on a Goode that the bottom had been painted with this and I thought it skied fine.