I've just updated a Keyword Favourite to exclude a word in the title. According to http://www.icetv.com.au/cgi-bin/websupport.cgi?op=show_faq&faq_id=151&faq_cat_id=23 this format should work "Cycling -BMX" but it removes all instances of the word Cycling too. I then tried without the quotes Cycling -BMX and it works.
I think the help page you referred to is correct, but a bit hard to read because of the way it uses quotes around the keywords, as well as when doing phrase searches. The page is updated now to be more clear on how keywords work. Take a look and see if it makes more sense: