Fairly new to cake decorating and have looked at tons of photos of cakes.
Some of the most awe inspiring are those that are covered in fondant and have perfect clean edges. I'm convinced these are not real cake, but styrofoam. Is it, in fact, styrofoam being used in these cakes?

Hi, some are dummies in mags and contests, but I find alot of the cakes on here that have those awesomely clean, sharp edges have ganache instead of BC. There's a great thread all about it. I have used this method a few times now and love it!
Check it out - http://cakecentral.com/cake-decorating-ftopict-633264-.html
Blessings~

I totally agree with bmoser24 about ganache. I'm also fairly new to all of this but I've learned so much from this site. And ganache was on of those things.

My edges are way smoother and sharper when I use ganache under my fondant. And another really great thing about ganache is that you don't have to worry about bulges!

And you can use any other BC too. It's all about chilling the cakes before fondant, and making them have a sharp edge before you put the fondant on. Very thin fondant as well.