Many of the cakes you'll see on here (like mine) are done for friends and family - so we're not selling them commercially, therefore they are being used for "home use". I suppose if the companies wanted to get really picky about it, they could sue us, but I think it would cost them more to file the suits than they'd be able to get out of us home bakers so they don't bother. It's when large commercial bakeries, and people who legally sell cakes out of their homes, routinely infringe on copyright laws that the big corporations like Disney get bent out of shape. The rule of thumb (for me anyway) is, if you aren't sure then don't do it.
Disclaimer (to be read in that really fast announcer voice): Eileen S. is not a lawyer, nor does she work for a large corporation that has trademarked characters. Any statements, comments, opinions and advice given by Eileen should not be taken as law. Please seek actual legal council if you are unsure. Batteries not included. Ken doll sold seperately.