S-urely abusable.
P-eople are trolls and haters.
A-bsolutely nonproductive.
M-aniacal idiots will spam the wall.
Deleting wont help, do you really want to waste your time deleting pages of spam?
Delete all button. And maybe the accounts would have to have to have a certain time as a member, like 6 months before you could do this to prevent alt abuse?