My view is that "smooth jazz" is more of a marketing category than a musical genre -- the result of applying a selection process to jazz. Perhaps what sticks in my craw is simply the impression that the selection process has excluded the particular kinds of jazz that I love to play. It's like a party that I don't want to attend until I find out that I haven't been invited. If they didn't use the word "jazz," then I probably wouldn't even notice. After all, it doesn't bother me that the music I love to play is also excluded from "light FM" and "all the hits all the time."