Using bootstrap default styles on a production site is lazy and shows a complete disregard for the art of design and front-end development. It's like buying a template from themeforest for $30 and changing the site title and name, except even worse: it's even less unique and more recognizable.
I am super particular and nitpicky about design and front end things and have an abnormally high level of attention to detail so for me any company that uses default bootstrap in production is automatically not legit (this may not be the case for others). A legit company has the time and resources to create a custom unique design and interaction style that is suited to their brand. A BS company does not, so they use bootstrap.
