I also looked at some SFH's in North Minneapolis bit as everyone around here knows that is a very undesirable place to live.

Read Florida Statute FS 509.141 titled Refusal of admission and ejection of undesirable guests; notice; procedure; penalties for refusal to leave.Hope this will help.

Do you know of any traditionally undesirable neighborhoods that will gentrify in 10 years?

Some sort of unified economic corp... probably a lot of undesirable areas banded together because there wasnt enough interest in the one specific neighborhood.

I had considered it but there are a few undesirable traits with the property that make me worry about holding it for 30 years or more.

Montebello - and most of the SGV is a very hot market - you're seeing some amazing appreciation in that whole area where even the neighboring cities that used to be undesirable have starting list prices of 500K!  

Ohio may be undesirable to some but the majority of us who are from here, love it here and aren't going anywhere.  

As far as crime rates goes, yes I understand the stats, but I also understand that there are many neighborhoods in Detroit that are gentrifying and its matter of finding the gems in the rough and firing the trigger..... pardon the punI  did this in Atlanta, I purchased in neighborhoods that were considered rough and undesirable at the time for around $35,000 today this SFH are worth $185,000 each and renting at on average $1400 pm. 

How about Peripheral Bay Area markets like Tracy, Livermore, Hayward Hills, or even Sacramento?

I recently got a call from an individual about a couple of condos he owns, but i looked them up on zillow & the estimation was 49k & they were also in a very undesirable area.