I would like there to be an option to search for questions that have been unedited. For example, a search for a question with edits might look like this: "hasedits:0 iOS animation". The syntax is similar to the syntax of the other search features like "hasaccepted:" and "isaccepted:" shown here.
Like Pekka, I don't see this search option having any purpose at all.
You've only identified one side of the search feature here. You say it would be nice to be able to search for posts in your tags that have never been edited. While the search results may yield something useful to you, you'd be just as likely finding something to edit without the extra search option. Whether or not a post has been edited before has absolutely no bearing on whether or not the post can be edited further.
Something which has never been edited may be in that state because there is nothing to edit, while something that has been edited three or four times could still have major issues that could be edited. I don't see how this search option would be helpful to the community.