Yes, I’ve been through them all. Most of theme resemble computers from the 90s. But I guess that’s XFCE’s defaults
It’s just a matter of taste, but it can also have security implications. So if people are used to ricing their Linux and that’s one of the first things they do (I did this immediately when I got Qubes), the might disregard the importance of the colors for domain disambiguation. Something that user research may uncover.
In the end I ended up settling for nodoka for the window borders, which is ok-ish. But I generally prefer more flat designs. I have described my XFCE customizations here.