I used to expect that if I stayed at a Marriott, I could assume that it would be in a good area that I could walk around in. I reserved the SHS at Miami airport East/Medical Center. After doing so read some of the reviews and discovered that it is in a bad neighborhood. Not good!
I actually clicked on this topic thinking of precisely that SHS. I stayed there for several nights a few years ago (early 2012, I believe), when my former employer's travel department booked me there for a trip involving the U. of Miami hospital. It's definitely not an area to be walking around by yourself at any time or at all at night. That said, I felt like the SHS had good security in place. Secure parking and security guards at the entrances.
AC Hotel in Bologna, Italy was located in an area that I would not have gone out after dark and feeling safe at all, in fact we walked into downtown Bologna and really kept our vigilance on high alert during the day. There was a park directly behind the hotel that our room overlooked and it seemed to have a number of people who just sat in the park area as if they were homeless, pulling garbage from the trash containers and just loitering.
Certainly not what I would have even thought of a spot a Marriott property would be located.