For some reason, Mona Lisa Overdrive suffered a number of terrible covers. The mass-market paperback with the most printings could be a cover for literally anything, which is better than the awful ones like the one you found. The competition for "worst sci fi cover art", by the way, is steep.
Oh man, back when I was reading through the Hugo winner list it was a victory parade of awful covers. There's a particular grossness to the 60s-70s era, but it's hard to say there's a time period where they don't suck. The other day I picked up one which has this exceptionally awful cover: It's bad enough that I had to hide the cover of it when leaving the bookstore, but I also have this terrible non-germane representation of the character corrupting my mental image of what the character was intended to be. Edit: OH almost forgot the worst part: red edge gilding on the book.
I think it was a problem of cheapness. There were lots of books, there were talented illustrators, but there wasn't enough money for every book to have a talented illustrator. I mean, that's peak Frank Franzetta time. Michael Whelan was rolling in. Vincent de Fate was everywhere. But you also got stuff like this: (also a Jack Vance, first book of Planet of Adventure, which your Jack Vance cover has also been used for:)
