It performs well given clean conversion signals and sensible structure. Most accounts give it neither.
You do not pick keywords. Google matches queries using your titles and attributes, so vague titles invite loose matching.
One blended ROAS target overspends on low-margin lines and starves profitable ones. Group products before automating.
Feeding profit instead of revenue often lowers headline sales while raising what you actually keep.
Disapproved products simply stop serving. It looks like weak performance, not an eligibility problem.