I think it's fair to say boring isn't the same as ugly and one person's boring is another's classic design.
You can argue most of the 'ugly' guitars are the adventurous designs or those trying to be different. And that the 'boring' ones are boring simply because they are popular, so you see many of them.
The basses that get the widest appreciation seem to be those that take one of the 'classic' designs and tweak it slightly, so it is at once familiar but distinctive.
A good test is to look at a bass of opposite hand to what you are used to. The asymmetry of a jazz bass really stands out this way, for example, and it seems quite radical.
But it's foolish to think ugly can be anything other than subjective.
The Hagstrom above is an 'ugly' I'd be happy to live with, as it is characterful.
Other people have Bongos or Alembics I think look absurd, yet others delight in them.
There's no right or wrong. It's like tortoiseshell versus plain scratchplates, natural wood versus painted. Neither makes any practical difference but some people get deeply offended by one or the other.