Here's a bad neighborhood in Chicago:
https://maps.google.com/maps?q=west+garfield+park&ie=UTF-8&h...
It is not well-maintained and it isn't pleasant; it's block after block of board-ups and red-X placards.
"Chicago's Auburn Gresham neighborhood made the list twice this year, but the census tract around South Halsted Street and West 77th is ranked highest at No. 4. Within a one-year period, NeighborhoodScout says there is a 1 in 9 chance of being a victim of violent crime here, and per 1,000 residents, the violent crime rate is 116.56.
The average per capita income in this area is lower than 99.4 percent of other U.S. neighborhoods, and 51 percent of children in this section of Chicago are living below the federal poverty line, giving this census tract a rate of childhood poverty that's higher than 93 percent of neighborhoods around the country."
I'll defer to your knowledge of Chicago, though. My point really is that while people talk about "bad neighborhoods" on the south side of Chicago, much (most? at least what I've driven through) is in pretty good shape. Even West Garfield Park isn't so bad in places. E.g. https://maps.google.com/maps?q=west+garfield+park&ll=41.8819...
I wouldn't want to drive down Washington in Garfield Park at night.
All of this is really not super relevant to your point, except to demonstrate that the neighborhoods people think of as "bad" in Chicago aren't pretty tree-lined residential streets that happen to have poor people living in them.
The whole point of development, especially development pursuant to the Olympics, is to push the poor out of the area. When any mayor says "we will clean up and develop this area," none ever mean "... in order to make a nice place to live for poor people." Indeed, if poor people still live there, the public won't even perceive the area as being nice.
E.g., this is one of the "bad neighborhoods" of Chicago: https://maps.google.com/maps?q=south+halsted+and+west+77+chi...
Like most of the city, it's actually quite well-maintained and pleasant. If lower-income people didn't live there, it wouldn't be considered a bad neighborhood at all.