Forums tend to suffer the 'loudest drunk in the bar' syndrome, and lose audience as a result.
I'd find an 'ignore' feature to be useful.
I could nominate posters I wish to ignore.
Threads started by them would not be displayed to me.
Replies made by them would not be displayed to me.
To hide posts made by people you want to ignore, add
to the user CSS in your profile for each person you tire of.
Quotes and threads in the list of threads don't get hidden though, nor do replies made to their posts. Maybe someone who enjoys playing with CSS more than I do will be able to provide a way.
Of course, this doesn't stop people like Beer who register a new username every week and it doesn't help this place looking like the worst community in the world to newcomers who don't have any custom CSS yet.