Emma, I have been noticing a huge daily influx of jibberish names on BlackSDA.com, as well. It is my understanding that these are usually robot-driven spam attempts. I'm surprised you are getting them here on Adventtalk because, while I don't remember if the safeguard was in place here when I registered here back in early 2008, I was told that new members must copy a picture of a group of letters in order to submit a request for membership. That step usually keeps these spam attempts from being successful.
I suppose it is possible that some clever person has created a program to defeat that safeguard.
GrandmaNettie