How to remove unused folders created by apps? When I started with a fresh SD card, there were only very few folders in it. As time passed by when I tried many apps, I could see the folder list in my SD card seems to grow.  

It is understandable that while an app is being uninstalled, it leaves behind its folder where it would have kept few files, which may be the settings file or game scores etc.

Is there any way I can remove all those orphaned folders in a batch or short operations? I have seen the question "How do one know which folder is created by which android apps" and can manually do it, but I am interested in kind of automatic solution.  

My phone info: LG Optimus One (P500) running stock 2.3.3 V20D (rooted).
Unfortunately, as the comments state, there is currently no way to automate this - and I for one wish there was, as I find myself deleting loads of folders as well.

You should do it manually - but methodically, and it starts to seem to take a lot less time, as you start to think about it.

One thing to look out for is folders for game apps that you installed, as they may contain the downloaded game data - which can be quite large, which you may wish to keep incase you want to install and play the game again.

Like Izzy mentioned, SD Maid finds some of the orphan files for you - but not all.