My answer for "so bad it is good" would be a list.
THIS would be on the list:
Think about this cast:
Michael Caine, Valerie Perrine, Brenda Vaccaro, Leonard Rossiter, Fulton Mackay, Jimmie Walker, Fred Gwynne
all in a movie that really has no reason to exist
But it does have a decent soundtrack.
And some rather funny gags, most of which were probably unintentional or ad libbed.
And, toward the end, some musical cameos that are almost worth sitting through the movie for.
.