Begs the question as to what a good one is though doesn't it ?

-Interior - what do you expect to find in a good one.
Any car that's done 100K miles or more will have sagging seats/bolsters and worn cloth/leather at the very least.

-Engine - should a "good" one have had a recent rebuild, there probably is no answer to how many miles a cossie should have before being rebuilt, but 125,000miles seems to be an agreed "must be done" sort of ballpark.

-Gearbox - Again, unless rebuilt, it will be sloppy after 15 years of abuse.

-Rust - again, any 15+ year old car used regularly will show some signs of rust, either existing, or, repaired in the past... Unless the car belonged to a bufty bufty.

As an example, mine is pretty much what I would expect of a car with 124,000 miles, the engine is in need of a rebuild, and there is rust on the chassis rails that needs attending to.

So, it's a good one in some respects, it's used daily, there are a few stonechips, etc... but again, all in all, it's fair wear and tear considering the mileage.