Cook spaghetti according to package directions. Meanwhile, in a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in the bacon, ketchup, pickles, barbecue sauce and mustard. Bring to a boil. Reduce heat; simmer, uncovered, for 5 minutes. Drain spaghetti; stir into meat mixture.
Sprinkle with cheese. Remove from the heat; cover and let stand until cheese is melted.