Some black holes are anything but black – and we've found more than 75,000 of the brightest ones

For a Black Hole to be defined, must have an Event Horizon, meaning the core prevents EMR from escaping .
So! All Black Holes look Black, in actual fact we cannot see beyond the EH.
The surroundings will show activity , sometimes an accumulation stars and or a dipolar vortices that can go for 100,000 light years.