Living in a mostly black suburb I can tell you:
In general (not all blacks) they are noisy, filthy and violent. That brings property value down.
When this was a mostly white community the only thing I had to pickup off my lawn before mowing were the twigs from the trees. Now my tree lawn is loaded with garbage. I don't bother cleaning it up anymore. I just take my leaf blower and blow it in the street. One time a police officer pulled up and asked me why I'm doing that? I told him it was not my garbage, it's the cities garbage since they don't do anything about littering here. He asked if I could just clean it up myself. I told him I don't clean up after filthy animals. That's what a zoo keeper does, and I am not a zoo keeper. He just drove away.
We used to have Fourth of July fireworks in my suburb, but that had to be put to a halt because you can't assemble any large group of blacks without it turning into gang fights or riots. We see that all the time in the news. Same goes for a church that used to have Vegas week. They had to close it down.
The noise here goes well into the morning hours. Now blacks are driving motorcycles and they have radios on them. The welfare blacks are out here 2:00, 3:00, 4:00 am blaring their jungle music on work nights that can be heard five houses away. They are the most inconsiderate race in the country. When it was all white, you could hear a pin drop because everybody in the suburb worked. Those who were retired respected those of us working and don't make the slightest noise.
We don't have one major store in our suburb anymore, even the Walmart moved out due to all the shoplifting by blacks. Others moved out because of armed robberies. Our police are in high speed pursuit at least once a week. We can't even keep police officers anymore.
So what normal person wants to live in such an environment? You can't have anything nice, people waking you up all hours in the summer when you have your window open, have to travel across town to the white areas to shop, scared to send your kids to our schools because of the violence and drugs, and that's what brings down property value.