It would include:

• Bad Referencing from incorrectly located files
• Difficult naming conventions for layers, blocks, hatches, etc.
• Essential files (like CTB files) located on local hard drives
• Settings that make plotting difficult
• Bad block definitions
• Incorrectly used Images
• Corrupted linestyle, multiline definitions
• Use of text fonts that are not standard SHX or TTF files
• Mismatched, incorrect, exploded and faked dimensions
• Inconsistency – Laziness
• Bad Viewports
• Bad Layout use and setup
• Failure to use OSnaps
• Faked files to get good plots
• Overly creative, innovative, advanced functionality
• Bad DWG exchange, export, save as, etc.