That's the problem with such listing. I think that for each car you will find people that dislike it, and that for each car you will also find people that like it.
So debating on what is ugly or not is a endless discussion, as the uglyness is, in most of the cases, very relative and depends on the tastes of everybody.
When you say "The Navigator is stunning, and elegant with its use of chrome", I rather agree with Neptune saying that this Lincoln is ugly
For that reason when doing a topic like this one it is quite useless to try to convince others that the cars that they mention as ugly are in fact beautiful. To take an example from "your" cars, I like that new Civic

For my part, those that I really find ugly are quite rare. Very rare.
From these mentionned above, there is the Fiat Multipla, the Subaru B9 Tribeca and the Ssangyong Rodius.
I'll add the Rexton

and especially the Actyon, still from Ssangyong

or the Nissan Murano



I could find others, but those that I mentionned are problably those that I like the least (from the recent cars, tough I do not think that there are some in older models that I dislike as much as those that I mentionned).

I know that the Pontiac Aztek is one of the most hated cars, but I actually find it good looking.