I've gotten to where these days I'm a lot more fond of having a "Content Notice" line than a "warnings" line, and in it I include things that legit need warning for, like non-con, etc., but also include things that don't needs warnings but people just might want to know, like top!Dean, dom!Sam, etc. And that's how I do it usually if it's like, non-penetrative sex or no sex at all but one is clearly more in control in the relationship, I'll use dom!Dean or dom!Sam instead of top, because they're the more dominant party. I don't know if that's confusing or if that's how other people do it, it's just how I've gotten used to doing it. *shrugs*

I'm one of those people that would like to know. I don't get squicked out if I start reading a story and find that the one who's my preference isn't the top or dom, but I do get mildly disappointed and usually lose interest. I guess it's just that I see the boys in certain ways, and like to read stories that characterize them that way. :P So it's good to know, but not something I think requires a warning, exactly.