People say long tail keywords are important to target in PPC campaigns, because not only are they targeted but also they cost a lot less to bid on. But when I searched for certain long tail key phrases, the adwords keyword tool said: Very Low Search Volume. Now what's very low search volume, is there a rough figure for this, like 100 searches per day? Or maybe, it's less. Now if that's the case, how can we bid on this key phrase, when its search volume is very low, nobody is searching for it. And if we don't get clicks (because nobody's looking for this), wouldn't google penalize us? Pl let me know if very low search volume is alright, or must we avoid such keywords altogether?