Are you talking about copying a layout of out of a scrapbook magazine or book? If so, that is why they put the books out. For ideas and motivation.
When you copy someone's page its called scraplifting and its accepted. When you have a scrapbook magazine its pretty much expected.
If you scraplift something out of the gallery, even if you make minor changes, its very nice to give them credit in your description. I think we all do that and I've seen my name pop up on several other scrapper's layouts.
If you lift them from a magazine or sketch book, then credit isn't necessary unless you have the artist name and would like to.