Direct Select tool selecting unnecessary groups
Steps to repeat making unecessary groups (just one of many ways) in order to test how they break the direct select tool, and cause unpredictable appearances:
1) make a rectangle.
2) apply a "3D Extrude & Bevel" effect
3) Expand appearance
Now that you've flattened your 3D object, you'll have an extra 4 unnecessary groups come along for the ride. But you won't know this unless you use Vector Firstaid, or use the appearance panel to manually inspect the situation (argh!).
4) Now use the direct select tool to click in the centre of one paths of the shape (direct select one of the paths – not a line or point)
5) look in the appearance panel
Expected behaviour: the appearance panel should display the path (as usual)
Actual behaviour: the appearance panel displays the (unnecessary) group above the path
Result: if you modify the appearance of the selection using the eye dropper, or the appearance panel, the modification is applied to the group. This appearance will interact with the appearances on the path bellow, as well as the (necessary) group above, causing anomalous behaviour. This requires the user to either manually enter the path appearance by double clicking in the panel, to manually remove the unnecessary group, or to use an additional paid plugin.
Unnecessary groups are a routine part of using Illustrator. They don't just add bloat - they get in the way of the direct select tool and cause unpredictable appearances.
Suggested solution: ensure that the direct select tool ALWAYS directly selects the target art item, and never a group.
Bonus points for creating fewer unecessary groups as a matter of course.