Flash a smartphone with vanilla Android ROM Is it possible to flash a smartphone like the Samsung Galaxy SIII or an LG Optimus 4X with a vanilla Android ROM like the one that has been flashed on Galaxy Nexus or Motorola phones (I think)?

I am asking because manufacturers like Samsung, LG, HTC tend to make ROMs for their smartphones and tablets with preinstalled launchers like Touchwiz or HTC Sense. They explain their decision by saying that they want to make their devices to look unique against their rival devices. The problem is that Android updates for their phones and tablets get delayed and there are incidents in which some devices - which are more than capable of running the upcoming version of Android - fall way behind or never get updated at all. 

So, what I am basically asking here is if there is a way to install vanilla Android, excluding CyanogenMod or any other modified vanilla ROMs, on an Android based smartphone?
Well Google only develops "vanilla" Android (called AOSP for Android Open Source Project ) for some selected phones (the Nexus Series). 

Manufacturers use this as base for their phone's OS. So you probably won't get a "vanilla" Rom from your manufactures, but there are probably a few AOSP-based Ports for your phone. (CyanogenMod is also based on AOSP) Rom-Developers tend to use an existing ROM like AOKP or Cyanogen as base because it's already compatible with a lot of devices. Porting "vanilla" AOSP is quite difficult and time-consuming because it lack's drivers and phone-specific code.