Messy data models (Re: Visualize database schema)

> Concerning auto-layout, most if not all tools I have used up to now
> make a mess for anything that is not dead simple.

If a data model can not be reasonably "untangled" by an auto-layout
algorithm (such as e.g. Graphviz) for display as a human-readable graph,
wouldn't that mean that this model is a mess from the modeling point of
view?

In fact, shouldn't reasonably well-designed data models at least mostly
follow SER principles? In that case, they could be displayed
essentially as a tree.

Could the "messy-ness" (or not) of the display of a data model (given
a standard alorithm such as Graphviz) be used as a criterion to judge
whether the model is actually well-structured?

Sincerely,

Wolfgang