Maybe its just that nobody has actually seen it... I am surprised nobody has mentioned "The Creeping Terror".
The movie was made in 1964 and was a late night TV staple during the early '70's. It was even heckled on MST3K.
In the film, a mysterious alien space ship crash lands on earth (an old film of an Atlas-Agena ICBM launch was played backwards to create the "special effect", and you could see "United States" printed on the side of the "alien craft").
The "creature" that emerged from the ship and terrorized the area was made out of a roll of shag carpet, and was so unweildy and difficult to move that the monster's victims had to hold still and in some cases help the monster swallow them. In some places, you could see the tennis shoes that the monster handlers were wearing. To make this turkey even worse, the entire story had to be told by a narrator, because some idiot accidentally erased the sound track.
I kid you not... ...this movie was actually released and is now available on DVD.
I disagree with someone's mention of "The Attack of the Killer Tomatos" That was MEANT to be bad... ...It is a Classic...