ButWeCould

Thats an example of a search grammar that I think is both: More simple and more flexible that evernotes current one. As i said author information is one alternative because you don't need to tag manually and exclusion works for that case. (Shared notes are tagged by their author so you might not exclude the notebook but you can excloude all notes not created by yourself)

While I very much think evernote SHOULD adress it's search syntax to be more flexible and consistend and that this is long long overdue. (I propose something like THIS.) One option to filter out shared notebooks is by author. You can exclude other authors by writing: -author:"Max Musterman" (mind the quotes)