No.
No, no, no, no, no.
Hav, the first rule of good karma systems is, they're never referred to as karma systems.
The second rule is, they function only on a scale of positive integers starting at zero. There cannot be bad karma.
The third rule is, the number attached to the karma system is not directly visible; you click a thank you/good poast button, and a hidden counter goes up until a useful contributor gets a shiny title like 'guru' or 'veritable toolbox' or some shit like that. This is something sometimes only mods are allowed to do, or whatnot, but basically its function is to help identify posters as useful to a community.
If (you as a mod thinks) a poster gains karma because of popularity, take their karma and give them a tallying marker for suspected popularity that is positive. IE, Ciarente gets a thousand karma points a week, and racks up four tallies of the 'heartbreaker' marker, as we can clearly attribute such things to popularity whoring, but does not get a 'fuck yeah, your posts are so awesome' title.
As such, this would be a system for stratifying contributors by behavior and reputation rather than by how many motherfuckers click a +1 button.