Publicity is a strong defense

But sometimes you may come to the application from the field outside of your expertise or even slight familiarity. Then you're not sure which site you can trust more. Obviously it's not only open source problem. A few years ago we had in Poland mks_vir vs ArcaVir "battle" (though it wasn't actually a redistributing thing but more, code acquisition/reuse and legality of it), where each side provided their own story. And similar cases possibly happen in local communities, which aren't bring up to world-wide media.