Good agencies report in leads and cost-per-lead against agreed targets; weak ones report in impressions, clicks, and 'engagement' — activity metrics that always look busy. If you can't state your CPL from their last report, the report is decoration.
The monthly questions that keep everyone honest: What did we spend? How many leads? What did each cost? What did we learn and change? A competent agency answers in ten minutes with numbers you can verify in accounts you own.
Fair judgment also needs fair clocks — paid search shows truth in ~60 days, SEO in ~6 months. Judge each channel on its native timeline, but never accept timeline as a reason for measurement not existing.