I mainly use the web interface and the iPhone App for creating new tasks. The new Smart Add Feature is really nice, but sometimes I forgot to add a priority or tags.

That's why I created a Smart List called "Check". It searches for tasks with one or more of these criteria:
- isTagged:false : Tasks without any tags and therefore not good to find.
- list:Inbox : Every task has to be in a specific list for me. Everything in the inbox has to be sorted.
- (NOT timeEstimate:"> 0") : Task without any time estimates.
- due:never : Without a due date means I will forget it completly.
- priority:none : Without a priority my tasks aren't ordered probably on my iPhone.

The complete search is:
isTagged:false OR list:Inbox OR (NOT timeEstimate:"> 0") OR due:never OR priority:none

I don't use the location, so it's not included. But you could easily add hasLocation:false for getting all tasks without a location.

Now I can open up the Smart List once a day and complete the specific tasks. As soon as you fill in the missed fields, the task will disappear from the Smart List.