I think the 1970s were the peak time for ugly knit sweaters. Followed closely by the 80s and 90s trend for sweaters and sweatshirts, often with shoulder pads in the 80s, decorated with a ton of gaudy applique, beads, you name it on the front.
I don’t find most “ugly sweaters” to be truly ugly, just super kitschy, which is fun.
I’d love to know how whoever picks the celebs for these “Christmas tree collage” sweatshirts chooses the celeb. I looked at a bunch before selecting a couple and the choices included a few recently popular rap stars and some major sports teams, which makes sense, but then these totally off-the-wall musical picks like Bob Seger, Weird Al Yankovic, Willie Nelson, Sheldon Cooper from Big Bang Theory, and Barry Manilow. The Manilow one is advertised as “Official Barry Manilow”. I wonder if Barry actually licensed them his images.