In English, few use the subjunctive "were" anymore. No one knows how or when to use "whom," and your/you're and their/there/they're makes me angry on a daily basis. In Spanish, conjugations are sometimes difficult for non-natives, seeing as they can be quite complicated. For native speakers, I find that many of them don't have a very extensive vocabulary. For example, I have yet to find a native Spanish speaker who knows how to say "drawbridge" (it's "puente levadizo").