By bad, do you mean incomplete or that it's often actually wrong? Because my experience is that it's very complementary and I see things on aerial that I didn't irl and of course also vice versa. Mapping from the air seems to work well to me
North Korea should be an interesting example, I guess we have no chance of anyone commenting on it but there's people who've been mapping it from actual satellite imagery, so very poor quality compared to the airplane-based georeferenced photographs we're used to in most countries. If armchair mapping makes bad maps, that will be the best example to have someone check out, but alas. (The visitor-accessible parts may not count as much because a mapper could have visited those)