Every deal is a different deal. I, too, have seen a lot of the properties in those areas. Some have been great buys - others are not.
You need to determine a few things:
1. How much do you have to spend on the purchase
2. How much would you have in reserve for repairs
3. Most importantly - what are the comparables for the area ...and make sure they are truly COMPARABLE.
4. What kind of financing can you obtain (if you are not a cash buyer)
When you have answered all of these questions, get with your buyer agent and decide on a case by case basis. Remember, LOCATION, LOCATION, LOCATION. Sometimes, if you are getting a good buy because of an external obsolescence, you will be giving someone else a good buy when you sell in the future. Some things can never be changed.
Let me know if I can help you further.