Although poor covers are not purely a self pub issue - there are some dreadful trad publish covers out there... something epitomised by the newer series of wordsworth classics https://electricliterature.com/these-book-covers-are-so-terrible-you-wont-believe-theyre-real/
you'd think so but apparently not... they were just very very cheap. also self pub does not have to be synonomous with poor quality covers... it is very easy these days to buy a premade or hire a designer
Yeah, I wouldn't say it's self pub vs trad pub. More like self made vs professionally made. That said, I make my own covers (haha). Though I wouldn't do so if I didn't think my quality matches with what I could afford to purchase but lord it takes me ages and a strange hyperfocus washes over me where I just keep working non stop all day. I also think genre has to do with it. I find my genre--paranormal romance--hit and miss with quality cover. They are strangely complex (design wise) and almost entirely about photo manipulation and that brings in a lot of variety of quality. Even when done by someone professionally making the covers. Then there are some genres that still pretty much demand a fully drawn cover and oh boy, I think the majority of us can easily say we are not qualified to do that.
I just keep my covers simple. They're only for me, as inspiration. I just grunge up an image (usually taken by me) so that it's almost an abstract, and then throw the book title and pen name on there in a suitable typeface.
I've heard some authors like to make inspiration boards on pinterest as visual inspiration as well. Talking about this makes me feel like I need to up my inspiration game.