I disagree with davidjohnson, yes those letting off steam will be in the majority but if you're getting disproportionately high volumes of negative comments compared to other airports then you have a problem.
If we're honest a lot of those airports at the bottom won't come as any surprise. Wouldn't have thought Bournemouth would be so low though!
It's hardly the first time either STN or LTN have been shamed, and I think to blame the methodology is clutching at straws somewhat.