Most of us are in agreement that inbound links can't lead to penalties, because if they did you could simply blast your competition with spammy links. But what about sabotaging their link velocity? You could, theoretically, send them quality links at a reasonable rate. After some time had passed, and they were lulled into passivity by their increasing SERPS, you could begin to quickly delete the links, therefore sabotaging their link velocity - actually making it negative - and probably delivering a blow to their SERPS, leaving them scrambling to get their link velocity back to a competitive level. I am not advocating this practice at all. It's just something that crossed my mind. Could this work?