I tend to avoid them like the plague. Granted, I have this one as a link in my bookmarks:
http://www.katfeete.net/writing/marysue.html
Yes that's the same one elvorg posted. =D. It's worthy of being linked twice.
I only have it there to serve as a reminder that some of the questions are utterly insane. I took it once or twice and I got good remarks at the end. But, some of the stuff doesn't apply to my characters at all. For example, it asks if the bad guys view him/her as hot. Now, what self respecting villain would go "Wow. He/she's kicking my *** but damn he/she is hot!" Kinda machostic isn't it?
Don't get me wrong. I like the quiz a lot but some of the questions it asks are insane and well, I would like a test that's more applicible to superhuman characters. In a reality where mutant powers are known and attained, there shouldnt be a sue connection if he/she can do fantastic things. As long as there's a reason behind it like being born that way or through some freak accident, it should be fine, right?
Like Psychic said, it depends wholly on the genre. I wouln't put my characters through an anime related litmus test because the things just aren't applicible. Like for instance there was one question asking if the character was wearing black. Umm. Yeah. Wearing black is the sign of a sue. Never mind if he or she is a covert ops specialist designed to work under cover of darkness wearing a black uniform.
To go with elvorg's comment, they do tend to ask for long explainations. I love how the tests all pyut singing as a possible sue trait when all it is is a hobby. I mean. How can singing be a sue? Sucks to be Dazzler from X-Men then. She made a whole carrer singing while being an X-Man. That and it goes perfectly with her sound based mutant powers.
Oh and that reminds me. The tests often ask if he/she is royalty. Again, I ask how is that a sue characteristic when there are tons of characters from Princess Jasmine from Aladdin to Princess Koriand'r (Starfire) who has some pull in government or are well off. To me, that's only a small part of who they are and one has to look deeper to see who they really are underneath the skin. You aren't going to call He-Man a Stu when in reality he's Prince Adam of Eternia.
So, social status really shouldn't be considered a sue trait and quizes lose points with me if they ask "Is he/she royalty?" Many characters in literature have been royalty and still manage to be great characters. That part just bugs me because you wouldn't go up to the princes of the UK and say "You're a stu! You're a prince and you joined the army!" That is if you can get within two yards of him...
I do have a question though. About hair color. How does it make it a Sue/Sue if He or she got green hair through birth like Polaris of the X-Men or through an accident like the Joker? Hair color shouldnt be a sue characteristic as people do also dye their hair. Check out fans of punk rock and you'll see what I mean. So, I'm just wondering about that. If there's a reason behind it, does that make them less of a sue/stu?
Anyway, I do like elvorg's link the best. Elvorg hit on the good points of the test. but, as a whole, they are kind of annoying because well some of the questions don't apply. I love the "Did your character feel responsible for a tragedy?" That points the finger at Batman and Spider-Man doesn't it? I don't see how that applies. But, then again I really want to see a test that does apply to my characters.
I've seen the pokemon one. That was an insane read.
LX
Edit: Dragonfree has a point though. Most tests do miss the point. I've put myself through a test. Damn. LOL. That was insane.