I couldn't agree more with JohnSmith, and also about the non-spanking elements vfrat mentions..
Personally I associate my views on this matter with my love for women - as a viewer, i want the spanker to be a woman - I want to watch her admiring the luscious rump on the spankee, while she administers the spanking, perhaps a touch of jealousy at how well endowed she is back there - all of that making it harder for her to resist the temptation to give her a furious walloping. If someone's having the fun, it may as well be a woman. I know F/M is off topic here, but on a somewhat related note, what well and truly puts me off about F/M is that in most cases the objectification continues to be restricted to the female spanker - the male is supposed to be an unfit looking old fart who enjoys pretending to be naughty and "getting it", which is a narrative that runs contrary to the naughty female spankee trope. Consequently, F/M scenes strike me as the sort where the women go in as robots, almost disgusted by the thought of having to smack a hairy male bottom( understandable!). If however, more women possessed the same sentiments as us males do - towards watching a "hot" male being spanked, it would make that variety a lot more appealing to some of us males. Admit it, what male among us (we'd have to be good looking but that applies equally to female spankees imo; as a wrestling fan watching Vickie Guerrero get spanked would do nothing for me) would not enjoy the thought of perhaps getting smacked in public by our gf and a group of girls watching and getting excited by it? The way we do for females receiving spanks? Flattering imo.
I guess what I'm trying to say is that M/F (to a certain degree) and F/M (entirely) are only preferrable to me if the male involved is myself - I wouldn't want to watch some other guy having all the fun, plain and simple. As a straight guy, considering I'm not attracted to males (To each his own), I'd rather have scenes like that enacted by myself, thank you very much. But when it's two women involved, pass the popcorn. Get it on! :)-D