Worst practices in Django you have ever seen
Too much logic in views. 
I used to write views that would struggle to fit in 40 lines. Now I consider more than 2-3 indentation levels, 10 or so LOC or a handful of inline comments in a view to be code smells.
The temptation is to write minimal models, figure out your url routing, then do everything else in the view. In reality, you should be using model methods, managers, template tags, context processors, class-based views with abstract base views... anything to keep the view code simple and readable. Logic around saving forms should go in Form.save(). Logic repeated at the start or end of multiple views should go in decorators. Reused display logic should go in included templates, template tags, and filters.
Long views are hard to read, understand, and debug. Learn to use the other tools in you toolkit any you'll save yourself and your team a lot of pain.
What are the worst mistakes made using Django framework, that you have noticed? Have you seen some real misuses, that maybe should go as warnings to the Django docs?