"Not a valid point?" That's an opinion - not a fact. Your statement applies equally to Gustin or other 'crowd-sourced' retailers. The business model may imply that funding an item gets you something that is made specifically for you -- but it doesn't work like that. Marketing materials need to be viewed with multiple huge grains of salt, regardless of the company from which the materials originate. But that won't stop me from ordering from Gustin again (or purchasing from Nordstrom or AE). If it did, then I wouldn't be buying anything from anyone.
Would I prefer a new, not tried-on pair? Probably. But it's not enough of a negative to get me to return a pair of shoes, as long as the visible signs of being tried-on are not more than what would occur within the first few hours of my own wearing of the shoes.