Parse “dressing badly” as “dressing as you would if clothes signaled nothing”. It is costly (social cost), and it is signalling, but it’s not costly signalling in the same sense as “I’m going to buy a suit instead of diamond-studded ice cream”.
Parse “dressing badly” as “dressing as you would if clothes signaled nothing”. It is costly (social cost), and it is signalling, but it’s not costly signalling in the same sense as “I’m going to buy a suit instead of diamond-studded ice cream”.