user122: I've just seen a cosplay-related question, which was posted during the definition-phase. 
http://area51.stackexchange.com/proposals/31538/anime-manga/31755#31755
There was a discussion, whether the question would be too objective, but I have an other question: Are cosplay-related questions on-topic in general?
I know, that a cosplay is always manga/anime-related, but isn't it more a question about dressing/photography? I don't know what question could come up, but I think, that cosplay-questions are most likely something like "How should I dress" "What's the best background" (See Photography.SE) ...

user126: The Area51 thread had a very interesting link, including Guidelines for Great Subjective Questions
I must say I love that blog post, and I believe if we demand open cosplay questions are allowed only if they fulfill premises described in there, we may get questions we really won't regret.
Thus, I think allowing them conditionally in the FAQ, along with this specific link as to how to phrase them would have a potential of adding to the value of the site.
Of course poorly written questions should be closed presto.

user41: Similar to my answer about Vocaloid questions, I think we have to limit cosplay-related questions to those that stem from the source material themselves. 
Questions about character outfits / design in a particular scene is one thing -- like asking about why Lina Inverse's hair changes colors at certain points in Slayers, or what the different rank insignia in FMA are (and what they look like) -- but actual questions about costume design and photography are too subjective and thus outside the scope of this SE.

user111: 
Some (if not most) of such questions are highly subjective ("what's the best way to...", "should I do X for cosplaying Y", and so on. 
The questions will most likely be about just the look, NOT about the character/story. A question about apparel might be ok if the question is directly connected to the story. (Example: Kempachi's eye patch and bells in his hair, which have concrete reasons of existence plot-wise). I'm sorry, but I personaly do not want questions like "how do I tie the ribbons in my hair the way Haruhi did on Sundays?". Forgive me this weakness.
Some of the questions are going to be like "where do I buy X to cosplay Y", or "How do I make X for my cosplay costume of Y".

For questions about how to make a costume/what fabrics or tools to use, something like this proposal will be better.
Subjective questions are off-topic on all SE sites. 
So, generally speaking I think such questions should be off-topic. 

122: <p>I've just seen a cosplay-related question, which was posted during the definition-phase. </p>

<p><a href="http://area51.stackexchange.com/proposals/31538/anime-manga/31755#31755">http://area51.stackexchange.com/proposals/31538/anime-manga/31755#31755</a></p>

<p>There was a discussion, whether the question would be too objective, but I have an other question: Are cosplay-related questions on-topic in general?</p>

<p>I know, that a cosplay is always manga/anime-related, but isn't it more a question about dressing/photography? I don't know what question could come up, but I think, that cosplay-questions are most likely something like "How should I dress" "What's the best background" (See Photography.SE) ...</p>
 126: <p>The Area51 thread had a very interesting link, including <a href="http://blog.stackoverflow.com/2010/09/good-subjective-bad-subjective/">Guidelines for Great Subjective Questions</a></p>

<p>I must say I love that blog post, and I believe if we demand open cosplay questions are allowed only if they fulfill premises described in there, we may get questions we really won't regret.</p>

<p>Thus, I think allowing them conditionally in the FAQ, along with this specific link as to how to phrase them would have a potential of adding to the value of the site.</p>

<p>Of course poorly written questions should be closed presto.</p>
 41: <p><a href="https://anime.meta.stackexchange.com/a/143/41">Similar to my answer about Vocaloid questions</a>, I think we have to limit cosplay-related questions to those that stem from the source material themselves. </p>

<p>Questions about character outfits / design in a particular scene is one thing -- like asking about why Lina Inverse's hair changes colors at certain points in Slayers, or what the different rank insignia in FMA are (and what they look like) -- but actual questions about costume design and photography are too subjective and thus outside the scope of this SE.</p>
 111: <ul>
<li>Some (if not most) of such questions are highly subjective ("what's the best way to...", "should I do X for cosplaying Y", and so on. </li>
<li>The questions will most likely be about <em>just the look</em>, NOT about the character/story. A question about apparel <em>might be ok</em> if the question is directly connected to the story. (Example: Kempachi's eye patch and bells in his hair, which have concrete reasons of existence plot-wise). I'm sorry, but I personaly do not want questions like "how do I tie the ribbons in my hair the way Haruhi did on Sundays?". Forgive me this weakness.</li>
<li>Some of the questions are going to be like "where do I buy X to cosplay Y", or "How do I make X for my cosplay costume of Y".</li>
</ul>

<p>For questions about how to make a costume/what fabrics or tools to use, something like <a href="http://area51.stackexchange.com/proposals/36782/clothing-and-fashion">this proposal</a> will be better.</p>

<p>Subjective questions are off-topic on all SE sites. </p>

<p>So, generally speaking I think such questions should be off-topic. </p>
