Disclosure: Have not and currently am not invested in Norristown.
I have looked at deals a few times in Norristown and couldn't get the numbers to work. Market rents didn't support the costs.
As both Joes mentioned, taxes. Taxes that are more than surrounding suburbs, in some cases, for a whole lot less in return.
There are better parts of Norristown that I'd say look no different than the higher value surrounding suburbs you mentioned.
I can't speak personally about inspections in Norristown but chatter from other investors say they are more onerous than they need to be.
A few rehab deals I analyzed looked okay until you realized that the property was in an "historic district" which meant you had additional exterior requirements. In my opinion, a bad joke on the part of Norristown to call run down blocks historic and force people that actually intend to improve properties to conform to make believe aesthetic preservation.
I do contend that it is still possible to make Norristown work if you find a good enough deal. Either Sheriffs sales or get lucky and find a motivated enough seller that needs cash NOW.
Edit:
https://www.montcopa.org/Docum...
The turnpike ramp / Lafayette Project I think will help gentrify that area a bit. It will likely be help make Norristown a more attractive suburb if the drive time is cut down for commuters. There is already good public transport to that immediate area but not everyone can use it for commuting.