For the badly written fics, it was about a year and a half ago. People would always post story threads that had overall bad grammar and spelling as well as ones that appeared as virtual "blocks" of text because nobody ever double-spaced their paragraphs like we require them to now. So the older staff members decided to establish base-line rules regarding quality of writing and use of proper formatting. Those are still the ones that are in place now, though several revisions and updates have been made as the general PB rules changed too.
As for the spambots, they've always been a nuissance, even before I became a staff member.