Substance is a much harder value to quantify. A man cannot tell you how reliable he is, he can only show it through action. Yes, there is always a need to consider the aesthetics of anything public facing, but what that is will change depending upon your audience.
Substance however, does not change. Substance is the grit of a man and how much steel he has in his spine, it is a behaviour that can be learned only with great difficulty and careful cultivation, and ultimately depends on the factors that make a man who he is.
In the vast majority of cases, substance is innate and unconscious. One should always look and dress well, but one should be concerned more with the substance of the men you recruit.
A few young lads in trackies have done more to stop Plantation centres going up in their area than the dozens in brown shoes and polo necks. The latter is maybe more aesthetic to the middle class; the former is definitely the group with more substance to them.