Currently Rylai's Crystal Scepter is on Teemo's recommended items list. The stats for this item are as follows:
> +300 Health
> +75 Ability Power
> Unique Passive: Damaging spells and abilities reduce enemy movement speed by 20% for 1 second.
Neither Teemo's Move Quick or Toxic Shot apply Rylai's passive, meaning that only two abilities, Blinding Dart and Noxious Trap, can proc this item. Furthermore, Teemo's Noxious Trap, "[slows Movement Speed by 30/40/50%](http://gameinfo.na.leagueoflegends.com/en/game-info/champions/teemo/)", meaning that the slow on his ultimate will always be better than (and override) Rylai's slow. Therefore, only Teemo's Q realistically benefits from Rylai's Crystal Scepter.
Seeing Rylai's Crystal Scepter listed under Teemo's recommended item's list caused me great confusion over whether or not his E procs the slow when I first started. To be honest, it still makes me do a double take at times, and I have level 7 mastery with Teemo, currently standing at 214,351 affinity points (or whatever they're called). Considering how the recommended items are designed to help players new to a champion, and how much confusion this causes, I suggest removing Rylai's Crystal Scepter from the recommended items list, even if experienced players will still choose the item from time to time, knowing full well that the slow only really works with Teemo's Blinding Dart.
I'm not trying to argue for or against using Rylai's Crystal Scepter on Teemo, I merely want to suggest that building such an item on him should be a choice made by experienced Teemo players based off their preferences and circumstances, and that other items are better recommended to summoners just trying out the champ.
If you are new to Teemo, I would be curious to see if having Rylai's Crystal Scepter recommended threw you off too. And if you are a Teemo veteran, is there any reason you can see for recommending this item to beginners that I overlooked? Thanks for taking the time to read this post, hopefully I won't get flamed for liking Teemo! ^_^