Lovecraft does use words like horrible and hideous often - but then, his stories are not told in first person. They are told to the reader by people who lived through some events. The reader is told he's listening to/reading someone's tale at the beginning, and that someone uses words like 'horrible' to describe the undescribable.
Unfortunately, many of today's readers can't imagine properly the feeling of sitting in a room, and listening to the story - instead they begin to assume they're actually the person telling the story, and they expect to be informed of the facts and get the feeling from the facts.
That said, I find Call of Cthulhu boring as well. I prefer "In the Mountains of Madness", which is much better suited to today's readers.
Also, I adore this approach to Lovecraft mythos:
http://www.macguff.fr/goomi/unspeaka...lt00-cast.html