I'm always looking for a mechanism that explains why otherwise sensible people behave strangely occasionally. I call it Charity
.
In this case I'm drawn to the idea that smelling two mints in the same minute or even hour will 'cant' your sense of smell for the second one. I'm constantly failing at comparing smells; even using a different hand to squeeze each leaf only helps with really different smells.
I also note that my wife is fully aware that she always says a wine is rubbish at the first taste, but her second taste and my first taste always agree.
Sadly it is very difficult to think of a way to exclude these vagaries of the nose.
I'm pretty sure that leaving lots of space between the 'mixed' and 'pure' beds will introduce enough variables to render the test pointless.
I'm also sure the people at Rothamstead have better things to do...
Cheers.