A Question for Artists about Critiquing

So here's the situation.

I'm going through the site and noticed a pic with a critique request.  Now I'm always game to give a critique if I've something to say, but in this case I just...don't, and I'm finding the reason I don't is bugging me.

Technically it's a good pic, an attractive female character from a TV show in a belly dancers outfit - this is literally the stuff my dreams are made of.    But the thing is, I've never watched the show and have no idea who this character is.  So......Look, if this was a pic of Raven, or Lady Jaye, drawn the same style, in the same outfit, I know for a fact that I'd have no problem writing a good critique about the pic.  I'd be fairly enthusiastic about it.  But because I have no context for the character I'm not finding anything about the pic that makes it stand out from the hundreds, if not thousands, of other decent pics of belly dancers on the site.

How do I express that in a critique?  How could I express that in a critique?  I'd literally be saying, "It would be a great pic if it were a character I liked, but because it isn't, it's kind of average."

But then...isn't this a valid critique?  Isn't the fact I find that the pic doesn't stand out something I should tell the artist?  Because, in my opinion this is a technically well done, but ultimately average picture.

But I'm finding I can't write that critique because, and I feel stupid saying this, I can't get over the feeling that my apathy towards the picture is more a failing on my end than the artists.  Because, as I said, if I knew who the character was I'd most likely have a better opinion of the pic. Even though being coldly logical about it, that nothing about he pic stands out is arguably on the artist.   

Opinions Please!