Hi @Stephen Scire
I´ve purchased a lot of occupied foreclosures over the years and the vast majority of them worked out well. It isn´t the easiest type of deal to start your journey with, but it´s doable if you have conservative assumptions and some more experienced people to get advice from regarding renovation, title, eviction etc.
First of all, make sure you do several drive bys of the house. If it is full of junk and badly maintained, chances are the interior is similarly poor. Look up the permit info for roof, AC, furnace etc. Look at recent/old MLS listings to see if you can get an idea of what the interior looked like in the recent past. Regardless, the majority of foreclosures, particularly multi families, need extensive cosmetic rehabs from top to bottom. If you buy a lot of these, you´ll notice that you get "unpleasantly surprised" far more often than "pleasantly surprised".
In terms of getting the previous owner out - cash for keys works best. In Florida, evictions are pretty straight forward and inexpensive. I don´t have any experience in Boston, but I think it is a lot more tenant friendly there, so be aware of how long you might need to hold onto that house before renovation starts.
Good luck and keep us posted!