i think those reduce to the first two types. paid shills is subjective and can be a domain expert. some even think krugman is a neoliberalist shill.

many hacks are also the first type. see degrasse tyson, jared diamond, malcolm gladwell, arguably pinker. very little substantive base, but great storytellers

activists reduces to the second type imo. if you have domain expertise, you usually hold a more nuanced view and don't come off as an activist even if you are very active. those with a preconceived notion are typically not a domain expert and just use their superior communication ability to prove their axe