The default concept can apply to image, title and content or description? and can correct details after...
Thinking how can post an advert more easy and faster,
e.g. Maybe I do not have pictures for my advert right now, but would like post it first and after adding more pictures what I want. Same situation with the content(e.g. This is my advert, by default), if I have more words, add it after, if not, that is all.
The image default will be good for admin or site advertisement use, for case if the user not have image for the advert.