What you want to look for is:
1. Engine performance. That includes idle quality, start-up hot/cold, backfires, etc.
2. Fuel mileage.
3. Seat of the pants. Down on power, etc. Would not pull the hat off of your head.
4. Spark plug readings.
5. Driveability issues including power sags, surges, etc. at any/all road speeds.
If any issues are noted, then they can be addressed.
One thing that can happen is if an engine is over-jetted. It seems to have lots of power, runs fine, but gas mileage will tank and excessive combustion chamber carbon could result. Might even foul plugs.
It is a delicate balancing act to dial it in correctly.