So, I found that our client JavaScript was recording quite a lot of successful dependency messages for loading 3rd party scripts:

Therefore, I wrote a telemetry filter to block sending them. I could just use sampling – but I’d prefer to have none.

onInit: function (sdk) {
	/*	Once the application insights instance has loaded and initialized this method will be called 
	    This filter will block successful remote dependency requests being logged. */
	sdk.addTelemetryInitializer(function(envelope) {
		if (envelope.baseType === 'RemoteDependencyData')
		{
			if (envelope.baseData.success)
			{
				return false;
			}
		}
	});
},

From my testing, if the user blocks loading of a remote dependency I don’t see any kind of message being returned – even a failure, which is good.