Blacklist can be very handy when searching under regions or a city.
When searching under a specific city name eg Nottingham, profiles created by a group called Adult Entertainments(Fake scammers, already discussed in a different thread),
regularly pop up, thereby getting in the way of other profiles you are trying to look at. At its peak, they had 30~40 fake profiles.
I'vce created an automatic search for within 15 miles of Nottm, so the blacklist becomes very handy, as it won't pick those profiles who've already been put in there. You simply add any new ones, thereby making the next search exclude any new ones you've added to the list.
Typical profile in their group
External Link/Members Only or
External Link/Members Only