BGP Peers as basis of available routes

Hi! We're currently evaluating web hosting providers in the APAC region and one of the criteria that we are currently considering is the availability of routes going to the web hosting provider. In this regard, I would like to ask for your idea regarding this. Is it safe to conclude that the web hosting provider's available routes would would depend on the peers who are advertising their AS / network? (i.e if web hosting provider claims that they are peering with telco a, b, c but as seen from a third party looking glass, only C is seen advertising the web hosting provider network that would mean web hosting provider is effectively utilizing c as their upstream??) Thanks. -- -nathan