Some people say a lot of sugar effects people skin by making them break out... Cake has a lot of sugar. However it really depends on the person, I could eat 5 pieces of black forest cake in a sitting and have nothing happen, where as someone who is effected by sugar could have a little bite of it and get a pimple
Like John said it really depends.
Cake could be bad or good for skin. A girl figured out to make a cake face mask and it seems to work for her. http://funadvice.com/r/bt28lun9qr1