I use yellow mustard when smoking pork solely for something that helps the rub stick. By the time the meat is smoked it is gone. Smoked some St Louis cut pork ribs today and used some yellow Plochman's mustard as a stickem'. Works for me.
So, you are saying my crock pot pork butt with liquid smoke and Kraft BBQ sauce is not true BBQ? Them's fight'n words! I will see you in the back alley tomorrow, just as soon as I finish my Cheez Whiz ball.