The answer is that each line ends with a word that looks like it rhymes with another word or other words in the poem but when sounded out, they don't. Such words are called eye rhymes, that the viewer of these eye-dentities must focus on the replication of letters that appear in the final syllable in each of two or more words and ignore the placement of stress.
Lederer, Richard; McKenty, Bob; and Gregory, Alexian
"A Foul Ghoul Soul Loves Good Blood Food,"
Word Ways: Vol. 38
, Article 2.
Available at: http://digitalcommons.butler.edu/wordways/vol38/iss2/2