This issue irritates me much. Somehow after installing wysiwig editor my comment body form turned into rich.. bla bla area. I do not want this but I can not find the place where to turn back comment input format to the plain text (or filtered format). I know how to change filter options for different content types but turning back comments to the simple format simply drives me crazy! Please help - where is this configuration place for comments?
here:
admin/structure/types/manage/[contentType]/comment/fields/comment_body
you could also set the format, in D7 at least ..