I noticed on cake boss that they steamed their cakes, Why do they do this?

it gets the powdered sugar or cornstarch off, it also makes the surface sticky if you wanted to add fondant cut outs.

You have to be very careful, I bought a steamer and I think I used it too high because it spat water all over my cake one time and it was really bad....

But it does get rid of the powdered sugar and stuff and give it a brighter look.

Although in certain cakes you can just go over it with a light spray of pearl dust (if its a pretty girly cake) and that helps even everything out, too.

I just use a mister and tighten the nozzle for the finest mist of water. Same effect.

If you have a cheaper, home grade steamer (like me ) You must make sure to keep the nozzle of the steamer high enough that water/condensation can't pool in a dip in the hose (does that make sense?) That's why you get spatters.
That having been said, you can still get drips, so you must be very careful around the cake. I love the shinier fondant look, so it is worth the risk to me.

Thanks to all for answering my question. I really love cc.

I use a clothes steamer I got at Walmart. I found, if I let it steam for about 5/10 minutes before I use it, I don't get any water spatters. I love the look on my cakes!

If you don't want to spend the money you can also brush our rub on a light coat of shortening like I did for my purse cakes.