Lizzie, I don't know if you listened to the entire Top 100 Motown songs, but I can imagine some of the less popular ones being dire, but also some very interesting ones.
I like Rock and Blues, but for every Lynyrd Skynyrd, Allman Brothers, AC / DC, Whitesnake, G & R etc, there's some appallingly awful bands like Kiss and Motley Crue etc.
Likewise in the early 60's, there were many good bands from Liverpool / Manchester, such as The Beatles, Searchers, Hollies, Big 3, but then there's the other side of the coin with joke 'bands' such as Hermans Hermits, Gerry & The Pacemakers and Freddie & the Dreamers, who musically were nowhere.
I could never take to pop bands such as The Tremoloes, Dave Clark 5, etc. Give me The Zombies and Spencer Davis any day.