a) It's unwise to attribute single-mindedness to a large group. In some cases it may be a plausible presumption. In other cases, not necessarily."when the base of a politician/political party ignores or even supports that politician during times of 'scandal', they are implicitly giving approval of that action, thus setting the bar even lower for the next politician. politics will eventually destroy us." SY #260
b) One plausible alternate, rather than an endorsement, it may merely be a presumption of innocence. And that can toggle from approval to disapproval once guilt is established.
c) The incremental degradation of standards which you've mentioned here has been a decades long pet peeve of mine. I appreciate your mentioning it. But unfortunately, the trend continues. And Trump may have kicked it into overdrive.