>"you could in theory have a black hole which has dark matter around it"
Well, the link I provided gave me the impression it is plausible that the black holes are dark matter. This sounds like a different idea than what you are rejecting as "possible but unlikely".
Well, ok. But apparently someone at NASA thinks it is plausible. Argument from authority heuristic tells me to listen to them rather than you in this case. Since you are not coming with any links or specific argument against what was said there, that is pretty much all I have to go on.
The interesting thing will be if we can prove they are around, which would then give some options for showing if they're dark matter or not (looking for gravity waves in areas where there's large dark matter concentrations would be the most likely candidate for now).
Well, the link I provided gave me the impression it is plausible that the black holes are dark matter. This sounds like a different idea than what you are rejecting as "possible but unlikely".