As someone who has spent the last 50 years encountering the song "Yummy Yummy, Yummy (I've Got Love in My Tummy)", which charted at #4 in the US in 1968 and has regrettably never really gone away, I'm hard-pressed to think of literally any song I've heard that's worse.
No, I haven't convinced you? 1969 #1 hit "Sugar, Sugar" by the Archies.
1969. The Beatles. The Stones. Jimi. Aretha. Otis. Leonard Cohen. The Kinks.
No. Turn on the radio. Yummy, Yummy Yummy I've Got Love in My Tummy. When you get to my age, and you hear that damned song for the thousandth time, you just want to give up. No amount of Katy Perry or Justin Bieber or whoever is going to be worse. Ever.