The icons you hate are icon set specific. I haven’t tried tinkering with them (I don’t actually use them, most of those plugins that come by default on most distros are removed on my installs), but I think you can change icon sets… or maybe themes (some themes also hold icon sets).
So, basically, you should install new icon sets and/or themes to get new icons and just pick one that you like, unistall the rest. Your default repo should hold most popular themes and icon sets for xfce.
PS: Some things may be inacurate, but I’m not much of a graphical person, I usually use xfce with default settings and maybe Greybird Dark as a theme. I leave everything else to default, whatever the defaults may be.