I did SEO for a pretty decent living and helped companies make multi-millions. My advice to the spammers is that an indie game site is highly irrelevant to sell kitchen knives or fake watches through.
Will they listen? Of course not.
Honestly, they should at least target relevant sights as the demographic isn't going to convert anyway. As it is, if IGS can't throttle it down, Google's algorithms are going to ding the page rank.
Lets keep these pests away from IGS.