I am in two minds about them. They drive page views but my audience is a broad one and these things can get complex.

I also missed the first one because, ironically, I was on a plane! And that was the one BA honoured .....

When Qatar is selling J for cash from Amsterdam etc to Asia for under £1,000, the mistake fares are also less interesting than they were - especially as Qatar is a better product and gives more tier points.