I do not agree w/ the Bloodthirster, but that simply isn't my playing style, maybe you completely destroy w/ it. I also sady don't agree w/ the armor penetration since Teemo as described to me by many amazing players is a AP/AS champion, but your build IS AD. I simply have my build 1 item different, the bloodthirster for a Rabadons deathcap. But I would recommend switching the armor pen, to magic pen.

Acually I like using Malady for the damage per hit and the damage bonus to poison dart, but I did try running this instead of mallet for a higher damage output. It's a good add instead of mallet I must say

You have put together a well-done guide, runes, masteries, and summoner spells. As for your items, you said you are going AD and you put in Malady. I will suggest The Black Cleaver as for it gives nice AD and a wealthy more amount of attack speed than Malady. Although it has a bigger cost it is worth it.+1