I would (and Have) check out the bike, give it a ride, give it a sprint, climb a short rise (if your area has one...). If all seems to operate well, and the frame & components show no damage.
If the bike rides as you expect. Then it's good.
Tires, bar tape, even saddle are expected consumables. I would always carry a chain checker to some used bike purchase scenario - if the chain is badly stretched, you may have to plan on replacing both the chain and cassette (worn cogs)...
It all dependenz...
If you're buying a pricey upper end used bike, you might want matchy matchy. If you're buying an older bike of any type, a mismatched wheelset is not a biggie, if the wheels checkout as good condition...
Ride On
Yuri