I have been working with fondant for about 6 months, and sometimes it works great but other times it doesn't. My problem is that I roll the fondant out, then I put it on the cake. But after I get it on the cake and smooth it out, the fondant is almost bumpy. I don't think that they are air bubbles though. I thought maybe I put too much powdered sugar down and that the powdered sugar stayed on the fondant in clumps in some places and other places there were no clumps, hence forming a bumpy appearance.

Nobody I have ever made cakes for has noticed this, but me being the perfectionist I am has noticed it, and has also noticed that a lot of cake pictures I have seen have very smooth fondant.

Thanks for any help!

you need to have a smooth surface under the fondant or it will show all the lumps and bumps.

Have you put a layer of something (piping gel, icing, marzipan) under the cake.
What kind of cake are you using?
As she ^^^ said, the cake must be almost perfectly smooth.
How thin/thick are you rolling the fondant? Maybe it needs to be thicker. It should be about the thickness of an average cake board (1/4").

Yes I put buttercream under the fondant. I get it all smoothed out and I usually put in the refrigerator for 15 or 20 minutes. Then I put the fondant on top of it. I was thinking it might have something to do with the powdered sugar because I usually use more to try and get it to not stick to the counter. It also almost seems that it could be a cake problem too. Almost seems like the fondant is too heavy and pushes the cake down causing the icing between the layers to spill out some. Could that be a problem?

could be use a denser cake. I notice when i use a straight up box mix then put fondant on it kind of looks rounded.

The thing i notice with fondant is its like when you paint a wall, you don't notice the imperfections in the wall until that nice smooth color is on top of it, then all of a sudden that little area that you didn't quite get sanded enough really shows up.