Check out Bicycling magazine from about 30 years ago.

At that time they comissioned Gary Klein (I think) who built the terantula, a fixture which measured frame flex when a measured load was applied to the crank arm. As I recall, the terantula data didn't compare very well with test rider's subjective assessments.

Bicycling doesn't conduct objective testing anymore - and they never encounter a product they don't like.