Its a gamble to go the permit route or not in Philly and absolutely matters the neighborhood/your neighbors as they are usually the folks that will call L&I on you OR if your property is near other construction sites where inspectors would be traveling to/from. 

@Cory Gamble do you have their contact number

Thats not a wise gamble in most cases if there is a market change for any unknown range of factors.

For all you know, the owner's late mother may have lovingly chosen the décor.

I would wait a while to get them at a discount but with condos, it always feels like a gamble because of future assessments, fee increases and difficulty getting a tenant approved in a timely manner.

Are you willing to gamble your life and those of your family on, "being accountable for your rentals", "being a good landlord", or "maintaining your properties correctly and being decent to your tenants"?

Regarding the most effective way to scale a real estate portfolio, it really depends on how passive you'd like to be, your chosen market/s and risk tolerance. 

@Tim Phillips I'd agree with your friends - rentals within driving distance are significantly easier to manage as well as decrease risk during the purchase process (because you can go see the property in person easily).I'd advise you to analyze as many properties as possible in your chosen market so that you have a good feeling for what a good deal in whatever market you pick is.

It can still work in niche situations but I think it is a grind and you gamble time and money. 

I have a nearly perfect credit score and I'm gambling on that for my first project.