No one ever remembers that stage lights don't emphasise every sinew like the shadowy post-gym/kitchen bathroom lighting of 2 weeks earlier.
It's not that they spill over or screw up their prep, it's that when they step out under stage lights all the detail washes out and they simply look less good than the next guy. Of course no BB is gonna admit they simply are not the best, so they say they would have won if they hadn't spilled over blah blah.