I figured out what the worst part about playing a Rogue is. Even if you're dropping things left and right with Assassinate, when you DO fail, everyone can see it. It's really obvious.
In EE content, I can get a very good success margin, but things can still save often. I try to Assassinate something, it saves, and I'm sitting there in stealth mode while the mob is attacking party members, thinking to myself "boy do I look stupid." Even when it's just a second before I start attacking normally, I'm sure someone in the group is thinking "poor rogue, he looks so stupid."
This is a problem that only Rogues have. It's very easy to tell when our instakill ability doesn't work. And it's kind of embarrassing.