Problem: LTR plugins in RTL blogs assume the admin is LTR when it's not.
Other than the aesthetics, it messes with forms. Inline checkboxes or radio buttons will sometimes show next to the wrong option (!!)
This can be fixed using direction: ltr; on untranslated plugins but in practice plugin authors don't do it.
(It's easy not to think about it when you don't use WP in RTL...)
A flag in the plugin's scope that determines whether the plugin writer has made it RTL compatible. If it's off, the plugin admin pages will get direction:ltr; . If it's on, the plugin author has the same freedom as they do today.